Structure Sentence Examples

A small door in the stone structure opened.

He formalized the structure of medical inquiry as an independent science.

From what I've learned his entire brain structure is distorted.

The structure of proteins enables scientists to understand the function they perform.

As Dean neared the structure, a figure emerged from the building.

A structure loomed darkly against the lighter horizon.

The structure was just under seventy feet long and about twelve feet high; said to be the height designed to accommodate a wagon fully loaded with hay.

She occupied the largest suite in the structure, seven spacious rooms on the top floor.

He passed the recently restored Beaumont Hotel, a beautiful structure that after several decades of disuse and deterioration had finally been returned to its past glory.

The children needed structure and direction in their lives.

On the farther side of the eastern ravine stands a smaller but very well proportioned structure, the church of St Eugenius, the patron saint of Trebizond, now the Yeni Djuma djami, or New Friday mosque.

I'm not easy to live with, and the structure is good for me.

The Teatro Farnese, a remarkable wooden structure erected in1618-1619from Aleotti d'Argenta's designs, and capable of containing 4500 persons, is also in this palace.

Her mother and father-in-law sat in front of the crushed structure, hunched over while their sobs reaching her ears.

I will begin by describing the structure of the school system in the Republic of Ireland.

Nearly seventy-five Colorado winters rusting away at the structure did not breed confidence.

The joists are covered with a waterproof material such as asphalt, lead, zinc or copper, the three last materials being usually laid upon boarding, which stiffens the structure and forms a good surface to fix the weatherproof covering upon.

These nations will play a substantial role in shaping this new English, as they bring grammatical structure, idioms, and nuanced words from their native tongue.

St. Thomas the Apostle Church was a scrubbed-white structure looking like a New England calendar except for its city loca­tion.

Such roofs are not suitable for cold climates, for accumulations of snow might overburden the structure and would also cause the wet to penetrate through any small crevices and under flashings.

The adobe structure was guarded by several more Guardians, none of whom looked like Damian from the distance.

Notwithstanding certain points of resemblance in structure and phonetics, Albanian is entirely distinct from the neighbouring languages; in its relation to early Latin and Greek it may be regarded as a co-ordinate member of the Aryan stock.

At the same time he felt that above his face, above the very middle of it, some strange airy structure was being erected out of slender needles or splinters, to the sound of this whispered music.

In 1894 and 1895, Fischer, in a remarkable series of papers on the influence of molecular structure upon the action of the enzyme, showed that various species of yeast behave very differently towards solutions of sugars.

The hotel de ville, also by Abadie, is a handsome modern structure, but preserves two towers of the château of the counts of Angouleme, on the site of which it is built.

Eventually he was able to prove that the biological doctrine of omnis cellula ecellula applies to pathological processes as well as to those of normal growth, and in his famous book on Cellular-pathologic, published at Berlin in 1858, he established what Lord Lister described as the "true and fertile doctrine that every morbid structure consists of cells which have been derived from pre-existing cells as a progeny."

You have the most beautiful bone structure.

The African elephant is a very different animal from its Asiatic cousin, both as regards structure and habits; and were it not for the existence of intermediate extinct species, might well be regarded as the representative of a distinct genus.

The small cathedral of St Aurea, also an early Renaissance structure, with Gothic windows, is by some ascribed to Meo del Caprina (1430-1501).

There are numerous modern churches and chapels, many of them very handsome; and the former parish church of St Nicholas remains, a Decorated structure containing a Norman font and a memorial to the great duke of Wellington.

The destruction was visible long before they reached the low adobe structure hidden between the foothills of the Tucson Mountains.

The Buen, as everyone referred to it, was located in a hundred year old structure previously known as the Scott-Humphries Building, which had remained vacant for over twenty-five years.

Pushing himself away from the book that would reveal nothing he sought, he went to the small, square window overlooking the stone structure of the Sanctuary.

Airy hallways led through the hacienda style structure on either side of her.

The structure of the mouth-parts is different from that seen in any other insects.

As a rule there is no allantoic placenta forming the means of communication between the blood of the parent and the foetus, and when such a structure does occur its development is incomplete.

The five-toed feet are of normal structure, and the rat-like tail is prehensile towards the tip. The female has a small pouch.

The plants show great diversity in vegetative structure.

In that world some structure was still being erected and did not fall, something was still stretching out, and the candle with its red halo was still burning, and the same shirtlike sphinx lay near the door; but besides all this something creaked, there was a whiff of fresh air, and a new white sphinx appeared, standing at the door.

World Wide Insurance Company was in the heart of Philadelphia, occupying a towering structure that glared down on city hall and a thousand tired buildings, many dating back to the horse-drawn carriage days.

They will have a two-tier governance structure - a Management Board and a Board of Governors.

Finally, there is the hypothesis that marsupials are the descendants of placentals, in which case, as was suggested by its discoverer, the placenta of the bandicoots would be a true vestigial structure.

The crystals are feebly doubly refracting, and in polarized light exhibit a banded structure parallel to the cube faces.

This genus comprises fresh-water polyps of simple structure.

It will be seen that from the biological standpoint there fall under the stricter definition those hereditary modes of behaviour which are analogous to hereditary forms of structure; and that a sharp line of distinction is drawn between the behaviour which is thus rendered definite through heredity, and the behaviour the distinguishing characteristics of which are acquired in the course of individual life.

The oesophagus is often furnished with glandular diverticula, the "glands of Morren," which are often of complex structure through the folding of their walls.

These worms lay cocoons like the Oligochaeta and leeches, and where they depart from the structure of the Oligochaeta agree with that of leeches.

There are two chitinous jaws in the buccal cavity, a dorsal and a ventral, which are of specially complicated structure in Cirrodrilus.

The nephridia are like those of the Oligochaeta in general structure; that is to say, they consist of drain-pipe cells which are placed end to end and are perforated by their duct.

Part of the present structure is believed to date from 1220 and once sheltered William Wallace.

The more modern buildings include the City Hall, a fine granite structure (completed in 1893), with a tower 180 ft.

Smith and fifty-nine others lost their lives; and St Paul's Church, where Jefferson Davis was attending services, on the 2nd of April 1865, when he received news from 1 As built in Richmond in 1845 by Luther Libby, it was a brick structure, three storeys high in front and four in the rear.

In this treatment we have to bear in mind what the entomologist teaches us, that is, the nature, habits and structure of the pest.

No general rules, applicable to all times, can be laid down as to what not only be prepared to take account of the physical features of the world, the general structure and organization of the industry and commerce of different states, the character of their administration and other important causes of economic change.

On this subject many monographs and larger works have been published in recent years, but dealing rather with such questions as trade unionism, co-operation and factory legislation, than the structure and organization of particular industries, or the causes and the results of the formation of the great combinations, peculiarly characteristic of the United States, but not wanting in England, which are amongst the most striking economic phenomena of modern times.

In dextral Gastropods the only structure found on the topographically right side of the rectum is the genital duct.

The general structure of the Molluscan intestine has not been sufficiently investigated to render any comparison of this structure of Patella with that of other Mollusca possible.

He defined structure " as the manner of the mutual linking of the atoms in the molecule," but denied that any such structure could give information as to the orientation of the atoms in space.

He regarded the chemical properties of a substance as due to (1) the chemical atoms composing it, and (2) the structure, and he asserted that while different compounds might have the same components (isomerism), yet only one compound could have a particular structure.

Identity in properties necessitated identity in structure.

Williamson showed how alcohol and ether were to be regarded as derived from water by substituting one or both hydrogen atoms by the ethyl group; he derived acids and the acid anhydrides from the same type; and from a comparison of many inorganic and the simple organic compounds he concluded that this notion of a " water-type " clarified, in no small measure, the conception of the structure of compounds.

The cathedral is a late Gothic structure begun in 1397 by Charles III.

It is astonishing how many good observers it requires to dissect and draw and record over and over again the structure of an animal before an approximately correct account of it is obtained.

The efforts of the best minds in zoology had been directed for thirty years or more to ascertaining with increased accuracy and minuteness the structure, microscopic and gross, of all possible forms of animals, and not only of the adult structure but of the steps of development of that structure in the growth of each kind of organism from the egg to maturity.

The assumption made was that (with the rare exception of parasites) all the change of structure through which the successive generations of animals have passed has been one of progressive elaboration.

It is Dohrn's merit to have pointed out 1 that this assumption is not warranted, and that degeneration or progressive simplification of structure may have, and in many lines certainly has, taken place, as well as progressive elaboration and in other cases continuous maintenance of the status quo.

The attempt to connect Mendel's observation with the structure of the spermcells and egg-cells of plants and animals has already been made.

It has a certain external and internal form, the latter being more usually called structure; 2.

Arcadia, on the other hand, in the heart of Peloponnese, retained till a late date a quite different dialect, akin to the ancient dialect of Cyprus, and more remotely to Aeolic. This distribution makes it clear (r) that the Doric dialects of Peloponnese represent a superstratum, more recent than the speech of Arcadia; (2) that Laconia and its colonies preserve features alike, -n and -w which are common to southern Doric and Aeolic; (3) that those parts of " Dorian " Greece in which tradition makes the pre-Dorian population " Ionic," and in which the political structure shows that the conquered were less completely subjugated, exhibit the Ionic -a and -ov; (4) that as we go north, similar though more barbaric dialects extend far up the western side of central-northern Greece, and survive also locally in the highlands of south Thessaly; (5) that east of the watershed Aeolic has prevailed over the area which has legends of a Boeotian and Thessalian migration, and replaces Doric in the northern Doris.

Sharp, is unlikely to be superseded by the result of any researches into minute imaginal structure.

Sharp's proposed association of the parasitic wingless insects in a group Anapterygota cannot, however, be defended as natural; and recent researches into the structure of these forms enables us to associate them confidently with related winged orders.

The Mecaptera, with their predominantly longitudinal wing-nervuration, serve as a link between the Neuroptera and the Trichoptera, their retention of small cerci being an archaic character which stamps them as synthetic in type, but does not necessarily remove them from orders which agree with them in most points of structure but which have lost the cerci.

This latter order, which is not certainly known to have existed before Tertiary times, has become the most highly specialized of all insects in the structure of the pupa.

The eruciform larva of the Orthorrhapha leads on to the headless vermiform maggot of the Cyclorrhapha, and in the latter sub-order we find metamorphosis carried to its extreme point, the muscid flies being the most highly specialized of all the Hexapoda as regards structure, while their maggots are the most degraded of all insect larvae.

They afford an example - paralleled in other classes of the animal kingdom - of an order which, though specialized in some respects, retains many primitive characters, and has won its way to dominance rather by perfection of behaviour, and specially by the development of family life and helpful socialism, than by excessive elaboration of structure.

And thus perfection of structure and instinct in the imago has been accompanied by degradation in the larva, and by an increase in the extent of transformation and in the degree of reconstruction before and during the pupal stage.

Like nearly all his predecessors since Aelian, he adopted an alphabetical arrangement, though this was not too pedantically preserved, and did not hinder him from placing together the kinds of birds which he supposed (and generally supposed rightly) to have the most resemblance to that one whose name, being best known, was chosen for the headpiece (as it were) of his particular theme, thus recognizing to some extent the principle of classification.3 Belon, with perhaps less book-learning than his contemporary, was evidently no mean scholar, and undoubtedly had more practical knowledge of birds - their internal as well as external structure.

During all this time little had been done in studying the internal structure of birds; 3 but the foundations of the science of embryology had been laid by the investigations into the development of the chick by the great Harvey.

That the series of natural animals is continuous, forming, as it were, a circle; so that, upon commencing at any one given point, and thence tracing all the modifications of structure, we shall be imperceptibly led, after passing through numerous forms, again to the point from which we started.

That these primary divisions of every group are characterized by definite peculiarities of form, structure and economy, which, under diversified modifications, are uniform throughout the animal kingdom, and are therefore to be regarded as the primary types of nature.

In these " Fragments," apparently his earliest productions, we find him engaged on the subject with which his name will always be especially identified, the structure and arrangement of feathers.

Two years later Nitzsch, who was indefatigable in his endeavour to discover the natural families of birds and had been pursuing a series of researches into their vascular system, published the result, at Halle in Saxony, in his Observationes de avium arteria carotide communi, in which is included a classification drawn up in accordance with the variation of structure which that important vessel presented in the several groups that he had opportunities of examining.

But it must be observed that the classification of Nitzsch, just given, rests much more on characters furnished by the general structure than on those furnished by the carotid artery only.

Hitherto our attention has been given wholly to Germany and France, for the chief ornithologists of Britain were occupying themselves at this time in a very useless way - not paying due heed at this time to the internal structure of birds, and some excellent descriptive memoirs on special forms had appeared from their pens, to say nothing of more than one general treatise on ornithic anatomy.

Here was found a rectangular structure resembling a temple, but with a side door to the north; it possessed a portico of six columns.

The prayer chamber is a lofty structure, quite unlike those of Egypt and Kairawan, with a dome 75 ft.

This section includes a brief history of the subject, and proceeds to treat of the principles underlying the structure and interrelations of organic compounds.

Additional evidence as to the structure of the molecule was discussed by Avogadro in 1811, and by Ampere in 1814.

This attitude was due to his adherence to the " dualistic theory" of the structure of substances, which he deduced from electrochemical researches.

Alexander Butlerow named the " structure theory," and contributed much to the development of the subject.

We have seen how its utilization in the " structure theory " permitted great clarification, and attempts were not wanting for the deduction of analogies or a periodicity between elements.

The ringed structure of benzene, C 6 H 61 was first suggested in 1865 by August Kekule, who represented the molecule by six CH groups placed at the six angles of a regular hexagon, the sides of which denoted the valencies saturated by adjacent carbon atoms, the fourth valencies of each carbon atom being represented as saturated along alternate sides.

The development of the " structure theory " in about 1860 brought in its train an appreciation of the chemical structure of the derivatives of benzene.

The value of this ringed structure was readily perceived, but objections were raised with respect to Kekule's disposal of the fourth valencies.

Here we shall only discuss the structure of these compounds in the light of the modern benzene theories; reference should be made to the articles Naphthalene, Anthracene and Phenanthrene for syntheses, decompositions, &c.

We may therefore conclude that the molecular volume depends more upon the internal structure of the molecule than its empirical content.

Hydrocarbons of similar structure have been prepared by Thiele, for example, the orange-yellow tetraphenyl-para-xylylene, which is obtained by boiling the bromide C6H4[CBr(C6H5)2]2 with benzene and molecular silver.

The quinonoid structure of many coloured compounds has been proved experimentally, as, for example, by Hewitt for the benzene-azo-phenols, and Hantzsch for triaminotriphenyl methane and acridine derivatives; but, at the same time, many substances cannot be so explained.

The development of the theory of crystal structure, and the fundamental principles on which is based the classification of crystal forms, are treated in the article Crystallography; in the same place will be found an account of the doctrine of isomorphism, polymorphism and morphotropy.

Isomorphism may be defined as the existence of two or more different substances in the same crystal form and structure, polymorphism as the existence of the same substance in two or more crystal modifications, and morphotropy (after P. von Groth) as the change in crystal form due to alterations in the molecule of closely (chemically) related substances.

Again, the pyroxenes, RS103 (R=Fe, Mg, Mn, &c.), assume the forms (I) monoclinic, sometimes twinned so as to become pseudo-rhombic; (2) rhombic, resulting from the pseudo-rhombic structure of (I) becoming ultramicroscopic; and (3) triclinic, distinctly different from (I) and (2); (I) and (2) are polysymmetric modifications, while (3) and the pair (I) and (2) are polymorphs.

It is doubtful indeed whether any general conclusions can yet be drawn as to the relations between crystal structure and scalar properties and the relative stability of polymorphs.

When both the crystal form and structure are retained, the substances are said to be isomorphous.

If the crystal structure be regarded as composed of 0 three interpenetrating point systems, one consisting of sulphur atoms, the second of four times as many oxygen atoms, and the third of twice as many potassium atoms, the systems being so arranged that the sulphur system is always centrally situated with respect to the other two, and the potassium system so that it would affect the vertical axis, then it is obvious that the replacement of potassium by an element of greater atomic weight would specially increase the length of w (corresponding to the vertical axis), and cause a smaller increase in the horizontal parameters (x and 1/ '); moreover, the increments would advance with the atomic weight of the replacing metal.

It is thus seen that the ordinary plane representation of the structure of compounds possesses a higher significance than could have been suggested prior to crystallographical researches.

In their minute structure the muscular fibres resemble those of Nematodes.

Alloa Park, the seat of the earl of Mar and Kellie, is in the immediate vicinity, and in its grounds stand the ruins of Alloa Tower, an ancient structure 89 ft.

For not only has the weight been more than quadrupled in some of the larger breeds, and the structure of the skull and other parts of the skeleton greatly altered, but the proportionate size of the brain has been reduced and the colour and texture of the fur altered in a remarkable manner.

This development, which is accompanied by changes in the structure of the skull, depends on breeding the animals in warm damp hutches, without which the best developed parents fail to produce the desired offspring.

These are large dogs, hunting by smell, with massive structure, large drooping ears, and usually smooth coats, without fringes of hair on the ears, limbs or tail.

The church of St Giles, formerly a chapel of ease to All Saints, but made parochial in the 18th century, is'of Norman date, but most of the present structure is modern.

The church of the Holy Ghost (Helgeands-Kyrka) in a late Romanesque style (c. 1250) is a remarkable structure with a nave of two storeys.

His writings, which are chiefly theological and controversial, are largely formed of charges to his clergy, and sermons on different topics; but, though valuable and full of thought, they lose some of their force by the cumbrous German structure of the sentences, and by certain orthographical peculiarities in which the author indulged.

It is nearly always a neat structure composed of fine twigs, roots or bents, and lined with wool or hair.

Pectolite is a secondary mineral occurring as white masses with a radially fibrous structure in the veins and cavities of basic igneous rocks.

In 1194 another conflagration laid waste the new building then hardly completed; but clergy and people set zealously to work, and the main part of the present structure was finished by 1240.

Thus the modern ideas, which have so powerfully extended and unified the subject, have loosened its connexion with "number" and "quantity," while bringing ideas of form and structure into increasing prominence.

Viewing the subject as a whole, and apart from remote developments which have not in fact seriously influenced the great structure of the mathematics of the European races, it may be said to have had its origin with the Greeks, working on pre-existing fragmentary lines of thought derived from the Egyptians and Phoenicians.

It is comparatively modern, built at different periods, a large and confused structure without proportion, beauty or strength.

The few remaining fragments produce the impression of vivid and rapid narrative, to which the flow of the native Saturnian verse, in contradistinction to the weighty and complex structure of the hexameter, was naturally adapted.

The ancient church of St Edward the Confessor was replaced in 1850 by a structure in Decorated style.

Approaching the coasts from the interior, the snow of the surface gradually changes its structure.

This is exactly the structure of the plum or apricot, and differs from that of the almond, which is identical in the first instance, only in the circumstance that the fleshy part of the latter eventually becomes dry and leathery and clacks open along a line called the suture.

It has, in fact, become metamorphosed into a resistant supporting structure resembling in some respects the notochord of the true Chordata, but probably not directly comparable with the latter structure, being related to it solely by way of substitution.

The respiratory current of water is therefore conducted to the exterior by different means from that adopted by Amphioxus, and this difference is so great that the theory which seeks to explain it has to postulate radical changes of structure, function and topography.

It seems likely that the coelomic pore-canals were originally excretory organs, but in the existing Enteropneusta the pore-canals (especially the collar canals) have, as we have seen, acquired new functions or become vestigial, and the function of excretion is now mainly accomplished by a structure peculiar to the Enteropneusta called the glomerulus, a vascular complex placed on either side of the anterior portion of the stomochord, projecting into the proboscis-coelom.

The state capitol, an imposing structure built on a bluff above the river, was built in1838-1842and enlarged in 1887-1888; it was first occupied in 1840 by the legislature, which previously had met (after 1837) in the county court house.

Another type of incipient crystallization which is excessively common in obsidian is spherulites, or small rounded bodies which have a radiating fibrous structure.

The minute globular bodies have occasionally a sub-pearly lustre, and glassy rocks which possess this structure have been called perlites (q.v.).

When it cools it becomes hard, but if before it is quite cold we plunge it into cold water a very perfect perlitic structure will arise in it.

If the matrix, however, is originally crystalline it does not seem probable that perlitic structure can develop in it.

A dull stony-looking rock results, the vitreous lustre having entirely disappeared, and in microscopic section this exhibits a cryptocrystalline structure, being made up of exceedingly minute grains principally of quartz and felspar.

Lowry and Armstrong represent these compounds by the following spatial formulae which postulate a y-oxidic structure, and 5 asymmetric carbon atoms, i.e.

This type of structure is somewhat common in Ireland, but the only Scottish examples are those at Brechin, Abernethy in Perthshire, and Egilshay in the Orkneys.

It was built on the site of an earlier structure entirely in the time of the Ptolemies.

The properties of caoutchouc clearly show, however, that its actual molecular structure is considerably more complex than is represented by the empirical formula, and that it is to be regarded as the polymer of a terpene or similar hydrocarbon and composed of a cluster of at least ten or twenty molecules of the formula C5H8.

When solid caoutchouc is strongly heated it breaks down, without change in its ultimate composition, into a number of simpler liquid hydrocarbons of the terpene class (dipentene, di-isoprene, isoprene, &c.), of which one, isoprene (C5H8), is of simpler structure than oil of turpentine (C 10 H 16), from which it can also be obtained by the action of an intense heat.

The exact chemical nature of caoutchouc is, however, not determined, and recent researches point to the view that its molecular structure may even be somewhat different from that of the terpenes.

Similar products are also formed by heating gutta-percha which closely resembles caoutchouc in its chemical structure.

The study of the action of ozone on caoutchouc has thrown new light on the complex question of the chemical structure of this substance, and discloses relationships with the sugars and other carbohydrates from certain of which levulinic acid is obtained by oxidation.

This arises chiefly from the orographical structure; the vast plateau of Central Asia prevents the moderating influence of the sea from being felt.

The American use of the term deltidium for the structure which Europeans call the pseudo-deltidium makes for confusion.

The term is also used generally of a supporting frame or structure, especially in the construction of a roof or a bridge.

In it the hairs are confined to the dorsal middle line and the creeping setae are hooked, of a finer structure than in Chaetosoma, and situated so far forward that the vagina opens amongst them.

It is in the Montagne Noire rather than in the Cevennes proper that the structure of the chain has been most fully investigated.

St Saviour's parish church of Tor-Mohun, or Tormoham, an ancient stone structure, was restored in 1874.

It is a fine cruciform structure of Decorated character, with a central tower 170 ft.

As a consequence of the structure of the molecule, which is an aggregation of atoms, the planes of the orbits around the latter may be oriented in various positions, and the direction of revolution may be right-handed or left-handed with respect to the direction of any applied magnetic field.

If the structure of the molecule is so perfectly symmetrical that, in the absence of any external field, the resultant magnetic moment of the circulating electrons is zero, then the application of a field, by accelerating the right-handed (negative) revolutions, and retarding those which are left-handed, will induce in the substance a resultant magnetization opposite in direction to the field itself; a body composed of such symmetrical molecules is therefore diamagnetic. If however the structure of the molecule is such that the electrons revolving around its atoms do not exactly cancel one another's effects, the molecule constitutes a little magnet, which under the influence of an external field will tend to set itself with its axis parallel to the field.

The castle is a quadrangular structure of great strength, with rounded towers at three of the angles, and has a circumference of about 400 ft.

The various comparisons previously made between the structure of Limulus and the Eurypterines on the one hand, and that of a typical Arachnid, such as Scorpio, on the other, had been vitiated by erroneous notions as to the origin of the nerves supplying the anterior appendages of Limulus (which were finally removed by Alphonse Milne-Edwards in his beautiful memoir (6) on the structure of that animal), and secondly by the erroneous identification of the double sternal plates of Limulus, called " chilaria," by Owen, with a pair of appendages (7).

Their minute structure is closely similar in the two cases; the leaf-like plates receive blood from the great sternal sinus, and serve as respiratory organs.

There is no doubt that these are parapodial or limb appendages, carrying numerous imbricated secondary processes, and therefore comparable in essential structure to the leaf-bearing plates of the second meso somatic somite of Limulus.

That is neces sarily a blood-holding structure and is obliterated and fused with soft tissues of the sternal region so that the lamellae cannot be detached and presented as standing out from it.

There are a number of other important points of structure besides those referring to the somites and appendages in which Limulus agrees with Scorpio or other Arachnida and differs from other Arthro- '11'1 poda.

The central nervous systems of Limulus and of Scorpio present closer agreement in structure than can be found when a Crustacean is compared with either.

The ommatidium (soft structure beneath the lens-unit of a compound eye) is very simple in both Scorpio and Limulus.

In the specialized ommatidia of the compound eyes of Crustacea and Hexapods the rhabdom is an important structure.'

A similar pair of coxal glands, lobate instead of ovoid in shape, was described by Lankester in Mygale, and it was also shown by him that the structures in Limulus called " brick-red glands " by Packard have the same structure and position as the coxal glands of Scorpio and Mygale.

Microscopically their structure is the same in essentials as that of the coxal glands of Scorpio (13).

The coxal glands do not establish any special connexion between Limulus and Scorpio, since thay also occur in the same somite in the lower Crustacea, but it is to be noted that the coxal glands of Limulus are in minute structure and probably in function more like those of Arachnids than those of Crustacea.

The entosternites are cartilaginous in texture, but they have neither the chemical character nor the microscopic structure of the hyaline cartilage of Vertebrates.

In microscopic structure they all present the closest agreement with one another.

A minute entosternite having the above-described structure is found in the Crustacean Apus between the bases of the mandibles, and also in the Decapoda in a similar position, but in no Crustacean does it attain to any size or importance.

Those of Limulus were described and figured by Alphonse Milne-Edwards, but he called them merely " transparent ligaments," and did not discover their muscular structure.

The minute microscopic structure of the gastric glands in the two animals is practically identical.

The most important difference which exists between the structure of Limulus and that of Scorpio is found in the hinder region of the alimentary canal.

Secondly, identity of structure in two organisms does not necessarily indicate that the identical structure has been inherited from an ancestor common to the two organisms compared (homogeny), but may be due to independent development of a like structure in two different lines of descent (homoplasy).

So, too, degeneration is not to be lightly assumed as the explanation of a simplicity of structure.

But little is known of the structure of these extinct animals; we are therefore compelled to deal with such special points of resemblance and difference as their remains still exhibit.

The general form and structure of their prosomatic carapace are in many striking features identical with that of Limulus.

The bi-ramose structure of the post-oral limbs, demonstrated by Beecher in the trilobite Triarthrus, is no more inconsistent with its claim to be a primitive Arachnid than is the foliaceous modification of the limbs in Phyllopods inconsistent with their relationship to the Arthrostracous Crustaceans such as Gammarus and Oniscus.

The form of the middle and lateral regions of the prosomatic shield has been used, and an excessive importance attached to the demarcation of certain areas in that structure.

The most important general change which has affected the structure of the nomomeristic Arachnida in the course of their historic development is the transition from an aquatic to a terrestrial life.

The lateral eyes of Limulus appear to be identical in structure and position with those of certain Trilobitae.

The Holosomata and Rhynchostomi are probably offshoots from the stem of the Araneae, and it is not unlikely (in view of the structure of the prosomatic somites of the Tartarides) that the Solifugae are connected in origin with the Pedipalpi.

Morphologically, the spiders are remarkable for the concentration and specialization of their structure, which is accompanied with high physiological efficiency.

The chief structure is the town hall, which is modern but has an ancient steeple.

The leading idea of Cuvier, his four embranchemens, was confirmed by the Russo-German naturalist Von Baer (1792-1876), who adopted Cuvier's divisions, speaking of them as the peripheric, the longitudinal, the massive, and the vertebrate types of structure.

The more cautious Cuvier adopted a view of the relationships of animals which, whilst denying genetic connexion as the explanation, recognized an essential identity of structure throughout whole groups of animals.

Cuvier's doctrine of four plans of structure was essentially a morphological one, and so was the single-scale doctrine of Buffon and Lamarck, to which it was opposed.

Cuvier's morphological doctikne received its fullest development in the principle of the " correlation of parts," which he applied to palaeontological investigation, namely, that every animal is a definite whole, and that no part can be varied without entailing correlated and law-abiding variations in other parts, so that from a fragment it should be possible, had we a full knowledge of the laws of animal structure or morphology, to reconstruct the whole.

Here Cuvier was imperfectly formulating, without recognizing the real physical basis of the phenomena, the results of the laws of heredity, which were subsequently investigated and brought to bear on the problems of animal structure by Darwin.

His homologous structures are now spoken of as " homogenetic " structures, the idea of community of representation in an archetype giving place to community of derivation from a single representative structure present in a common ancestor.

The greatest of all investigators of animal structure in the 19th century was Johann Miller (1801-1858), the successor in Germany of the anatomists Rathke (1793-1860) and Meckel (1781-1833).

He showed (1830) that the organisms like Flustra are not hydroid Polyps, but of a more complex structure resembling Molluscs, and he gave them the name Polyzoa.

Contemporaneous with these were various schemes of classification which were based, not on a consideration of the entire structure of each animal, but on the variations of a single organ, or on the really non-significant fact of the structure of the egg.

It is to be noted that, whilst the zoological system took the form of a genealogical tree, with main stem and numerous diverging branches, the actual form of that tree, its limitation to a certain number of branches corresponding to a limited number of divergences in structure, came to be regarded as the necessary consequence of the operation of the physico-chemical laws of the universe, and it was recognized that the ultimate explanation of that limitation is to be found only in the constitution of matter itself.

The pre-Darwinian systematists since the time of Von Baer had attached very great importance to embryological facts, holding that the stages in an animal's development were often more significant of its true affinities than its adult structure.

Weismann has also ingeniously argued from the structure of the egg-cell and sperm-cell, and from the way in which, and the period at which, they are derived in the course of the growth of the embryo from the egg - from the fertilized egg-cell - that it is impossible (it would be better to say highly improbable) that an alteration in parental structure could produce any exactly representative change in the substance of the germ or sperm-cells.

It has been argued that the elaborate structural adaptations of the nervous system which are the corporeal correlatives of Theory complicated instincts must have been slowly built up by the transmission to offspring of acquired ex perience, that is to say, of acquired brain structure.

Observed through this the structure of some wire gauze just disappeared at a distance from the eye equal to 17 in., the gauze containing 46 meshes to the inch.

But it is possible that, as suggested by Rowland,' the structure of natural spectra may be too coarse to give opportunity for resolving powers much higher than those now in use.

But in addition to these distinctive characters, living matter has some other peculiarities, the chief of which are the dependence of all its activities upon moisture and upon heat, within a limited range of temperature, and the fact that it usually possesses a certain structure or organization.

Living things which present this visible structure are said to be organized; and so widely does organization obtain among living beings, that organized and living are not unfrequently used as if they were terms of co-extensive applicability.

But practical necessity has given rise to the existence of many other divisions; see CYTOLOGY, for the structure of cells; EMBRYOLOGY, for the development of individual organisms; HEREDITY and REPRODUCTION, for the relations between parents and offspring.

This structure can be rendered visible by superficial etching with dilute acid; and as the minuter crystals dissolve more quickly than the larger ones, the surface assumes a frosted appearance (moiree metallique).

The two systems of folds meet about Barquisimeto, where the structure becomes very complex and is not thoroughly understood.

Pacas may be distinguished from agoutis by their heavier and more compact build, the longitudinal rows of light spots on the fur, the five-toed hind-feet, and the peculiar structure of the skull, in which the cheek-bones are expanded to form large capsules on the sides of the face, each enclosing a cavity opening on the side of the cheek.

The localization of function in the cerebral and in the cerebellar cortex has doubtless been the main cause of this progress, and has proceeded poi passu with an extended insight into the structure and connexions of the parts concerned.

Health is simply that condition of structure and function which, on examination of a sufficient number of examples, we find to be commonest.

Disease we may define, accordingly, as any departure from the normal standard of structure or function of a tissue or organ.

If, for instance, we find that instead of the natural number of Malpighian bodies in the kidney there are only half that number, then we are entitled to say that this defect represents disease of structure; and if we find that the organ is excreting a new substance, such as albumen, we can affirm logically that its function is abnormal.

According to our present knowledge of physiological and pathological processes, we must regard the cell as the ultimate biological unit - a unit of structure and a unit of function; this was first put forward by Schleiden in 1838, and by Schwann in 1839, but we owe to Virchow the full recognition of the fundamental importance of the living cell in all the processes of life, whether in health or disease.

Until, however, further evidence is forthcoming in support of this syncytial theory of structure, it would be unwise to regard it as established sufficiently to constitute a serviceable working hypothesis; hence, for the time being, we must accept the assertion that the cell represents the ultimate tissue-unit.

According to the hypothesis of Waldeyer and Thiersch there is perfect equilibrium between the normal epithelium and its supporting structure, the connective tissue, but with advancing age this balance is upset owing to the connective tissue gradually losing its restraining power.

They may at some later date become active in some way, and so give rise to a cellular proliferation that may imitate the structure in which they grow, so giving rise to new growths.

Not only is this true of epithelial cells, but - the connective tissuecells of the supporting structure of cancerous growth, after repeated transplantation, may become so altered that a gradual evolution of apparently normal connective tissue into sarcomatous elements takes place, these giving rise to " mixed tumours."

The name "mountain house" suggests a lofty structure and was perhaps the designation originally of the staged tower at Nippur, built in imitation of a mountain, with the sacred shrine of the god on the top. The tower, however, also had its special designation of "Im-Khar-sag," the elements of which, signifying "storm" and "mountain," confirm the conclusion drawn from other evidence that En-lil was originally a storm-god having his seat on the top of a mountain.

The structure and functions of the body form the subject of Anatomy (q.v.) and Physiology.

It is clear that the knowledge of function (physiology) did not by any means keep pace with the knowledge of structure, and this was probably the reason why the important sect of the empirics were able entirely to dispense with anatomical knowledge.

In 1872, Hoppe-Seyler (1825-1895) gave a new beginning to our knowledge of the chemistry of secretion and of excretion; and later students have increased the range of physiological and pathological chemistry by investigations not only into the several stages of albuminoid material and the transitions which all foodstuffs undergo in digestion, but even into the structure of protoplasm itself.

But bodily defect is largely a result of evil circumstances, in the prevention of which the physician is not unsuccessfully engaged, and the growth of sympathy means a stronger cement of the social structure.

Not, however, all diseases of the nervous system conduct themselves on these definite paths, for some of them pay no attention to the geography of structure, but, as one may say, blunder indiscriminately among the several parts; others, again, pick out particular parts definitely enough, but not parts immediately continuous, or even contiguous.

Diseases of the latter kind are especially interesting, as in them we see that parts of the nervous structure, separated in space, may nevertheless be associated in function; for instance, wasting of a group of muscles associated in function may depend on a set of central degenerations concurring in parts whose connexion, in spite of dissociation in space, we thus perceive.

Many other diseases formerly regarded as primarily diseases of the nervous system are not such; but, by means of agents either introduced into the body or modified there, establish themselves after the affinities of these in contiguous associated parts of the structure, as in vascular, membranous or connective elements, or again in distant and peripheral parts; the perturbations of nervous function being secondary and consequential.

It is in the structure of the brain itself that modern research has attained the most remarkable success.

It is a massive stone structure of nine arches, carrying a level roadway, and is considered one of the finest bridges of its kind in the world.

Finally, the surface topography will often throw much light on the underground structure.

Unable to accept Berzelius's doctrine of the unalterability of organic radicals, he also gave a new interpretation to the meaning of copulae under the influence of his fellow-worker Edward Frankland's conception of definite atomic saturation-capacities, and thus contributed in an important degree to the subsequent establishment of the structure theory.

The structure of glass has been the subject of repeated investigations.

C. Maxwell Garnett, who has studied the optical properties of these glasses, has suggested that the changes in colour correspond with changes effected in the structure of the metals as they pass gradually from solution in the glass to a state of crystallization.

The crystalline structure which exists on both sides becomes visible only in the metals of the first class, and only there manifests itself as brittleness.

Closely related to the structure of metals is their degree of "plasticity" (susceptibility of being constrained into new forms without breach of continuity).

In the design of a structure such as a tall reservoir dam it is important that the line of thrust in the material should pass inside the core of a section, so that the material should not be in a state of tension anywhere and so liable to open and admit the water.

The town cross is a fine structure standing upon a huge hexagon, surmounted by a stone pillar 12 ft.

While the Martello tower owes its reputation and its widespread adoption in Great Britain to a single incident of modern warfare, the round masonry structure entered by a door raised high above the base is to be found in many lands, and is one of the earliest types of masonry fortification.

Our knowledge of the chemical structure of the monosaccharoses may be regarded as dating from 1880, when Zincke suspected some to be ketone alcohols, for it was known that glucose and fructose, for example, yielded penta-acetates, and on reduction gave hexahydric alcohols, which, when reduced by hydriodic acid, gave normal and secondary hexyliodide.

Ruff effects the same change by oxidizing the sugar to the oxy-acid, ' See Fermentation; and for the relation of this property to structure see Stereoisomerism.

We can now proceed to the derivation of the structure of glucose.

It is traversed by a canal from which a peculiar proboscis-like structure can be exserted.

The two genera agree closely in form and structure and may possibly belong to the cycle of the same or of allied species.

The finer structure of the animal has been investigated by Mrazek (to), whose account, however, is published in the Hungarian language.

The scolex is usually a conical muscular structure.

The extraordinary variety of form and complication of structure exhibited by the appendages of the scolex are adaptations to fix FIG.

Those Cestodes which possess no very distinct organ of attachment (such, for example, as Gyrocotyle) have no distinct ganglionic thickening more pronounced at one end of the body than at the other; and as these are forms which have retained more primitive features than the rest, and show closer affinity to the Trematodes, it seems highly probable that the complicated nervous thickening found in the scolex, and often compared with the " brain " of other Platyelmia, is a structure sui generis developed within the limits of the sub-class.

The structure of these organs is seen in figs.

In a few genera the place of the chitinoid coat is taken by a ciliary investment and in most families the structure of the layers is characteristic.

The prime object of interest is the cathedral of St Magnus, a stately cruciform red sandstone structure in the severest Norman, with touches of Gothic. It was founded by Jarl Rognvald (Earl Ronald) in 1137 in memory of his uncle Jarl Magnus who was assassinated in the island of Egilshay in 1115, and afterwards canonized and adopted as the patron saint of the Orkneys.

To the east of the remains of the bishop's palace are the ruins of the earl's palace, a structure in the Scottish Baronial style, built about 1600 for Patrick Stewart, 2nd earl of Orkney, and on his forfeiture given to the bishops for a residence.

In a fit of jealousy the emperor commanded that this masterpiece should be thrown down, and sent commissioners to Amber charged with the execution of this order; whereupon Mirza, in order to save the structure, had the columns plastered over with stucco, so that the messengers from Agra should have to acknowledge to the emperor that the magnificence, which had been so much talked of, was after all pure invention.

The caliche has often a granular structure, and is yellowishwhite, bright lemon-yellow, brownish or violet in colour.

Stomata occur on both surfaces of the leaves, and, with the peculiar hair structure render the microscopic appearance of the plant highly characteristic.

The plants are of extremely simple structure and are the smallest and least differentiated of flowering plants.

They consist of a so-called "frond" - a flattened green more or less oval structure which emits branches similar to itself from lateral pockets at or near the base.

These were by no means the only rights and duties which could be described as existing in feudalism, but they are the most characteristic, and on them, or some of them, as a foundation, the whole structure of feudal obligation was built, however detailed.

The Forficulidae are almost cosmopolitan; but the various species and genera differ from each other both in structure and size to a comparatively slight extent.

Of particular zoological interest in this connexion is a Ceylonese genus Dyscritina, in which the cercopods are long, many-jointed and filiform during the early stages of growth, and only assume at the last moult the forcipate structure characteristic of the family.

The nest is a neat structure of coarse grass and moss, mixed with earth, and plastered internally with mud, and here the female lays from four to six eggs of a blue colour speckled with brown.

In the absence of face-glands and in the structure of the horns the species approximates to the goats.

Famous as the one stone structure is in that stoneless region, the post became known far and wide amongst the hordes of the steppe as Sar-kel or the White Abode.

After discussing the structure of the eye he gives an experiment in which the appearance of the reversed images of outside objects on a piece of paper held in front of a small hole in a darkened room, with their forms and colours, is quite clearly described and explained with a diagram, as an illustration of the phenomena of vision.

Normandy's apparatus, although economical and producing water of good quality, is very complex in its structure, consisting of very numerous working parts, with elaborate arrangements of pipes, cocks and other fittings.

The parish church of Au, in the Early Gothic style, contains gigantic stained-glass windows and some excellent wood-carving; and the church of St John in Haidhausen is another fine Gothic structure.

Their structure has undergone little degeneration in connexion with this habit, and may be compared organ for organ with that of the Planarians.

In most endoparasitic Trematodes the accessory gonopore is a median and dorsal structure.

The anatomical structure of the Trematodes is fairly uniform (Braun).

The structure of a redia, however, is an advance on that of its parent.

The tail may be a simple hollow muscular process or provided with stiff bristles set in transverse rows, or divided into two equally long processes, or finally it may form a large vesicular structure.

In the vibraculum the part representing the zooecium is relatively smaller, and the mandible has become the "seta," an elongated chitinous lash which projects far beyond the zooecial portion of the structure.

They occur in particular in relation with the orifice of the zooecium, and with that of the compensation-sac. This delicate structure is frequently guarded by an avicularium at its entrance, while avicularia are also commonly found on either side of the operculum or in other positions close to that structure.

It is terminated by a well-developed structure (fg) corresponding with the apical sense-organ of ordinary Trochospheres, and an excretory organ (nph) of the type familiar in these larvae occurs on the ventral side of the stomach.

The alimentary canal, which may be represented by a vestigial structure, is accordingly not functional, and the larva does not become pelagic. A pyriform organ is present in most Gymnolaemata as well as the sucker by which fixation is effected.

If the Phylactolaemata were evolved from the type of structure represented by Phoronis or the Pterobranchia, the Gymnolaen ata should be a further modification of this type, and the comparative study of the embryology of the.two orders would appear to be meaningless.

The whole apparatus is so exactly analogous in structure to the poison-gland and tooth of a venomous snake as to suggest a similar function, and there is now evidence that it employs this organ as an offensive weapon.

P. Smith discusses "The Strophic Structure of the Book of Micah" in a volume of Old Test.

It is no detriment to Comte's fame that some of the ideas which he recombined and incorporated in a great philosophic structure had their origin in ideas that were produced almost at random in the incessant fermentation of Saint-Simon's brain.

The church was remodelled in 1139, to which period much of the existing structure belongs, including the richly sculptured west front and the open confessio or crypt, which occupies the eastern half of the church, raising the choir high above the nave.

The most interesting of these is the Alte Mainbriicke, a red sandstone structure of fourteen arches, 815 ft.

Other bridges are the Obermainbriicke of five iron arches, opened in 1878; an iron foot (suspension) bridge, the Untermainbriicke; the Wilhelmsbriicke, a fine structure, which from 1849 to 1890 served as a railway bridge and was then opened as a road bridge; and two new iron bridges at Gutleuthof and Niederrad (below the city), which carry the railway traffic from the south to the north bank of the Main, where all lines converge in a central station of the Prussian state railways.

North and east of the Fossa Magna the structure is concealed, to a very large extent, by the outpourings of the volcanoes which form so marked a feature in the northern part of Hondo.

The pillars, architraves, ceilings, panels, and almost every available part of the structure, are covered with arabesques and sculptured figures of dragons, lions, tigers, birds, flowers, and even pictorial compositions with landscapes and figures, deeply carved in solid or open workthe wood sometimes plain, sometimes overlaid with pigment and gilding, as in the panelled ceiling of the chapel of Iyeyasu in Tokyo.

The avenue of approach generally passes under a structure called toni.

The structure derives some grace from its extreme simplicity.

The church of St Nicholas is a fine Perpendicular structure exhibiting the flint-work common to the district, and possessing a beautiful south porch and the ruin of a massive western tower which partly collapsed early in the 18th century.

On the other hand, he advances too easily from the maxim that function is prior to, and makes, structure to the conclusion that the results of use and disuse are therefore immediately incarnated in structural adaptations capable of hereditary transmission.

Lastly we have the white - Burchell's, or square-mouthedrhinoceros (Rhinoceros (Diceros) simus), the largest of the five, and differing from the other species in having a square truncated upper lip. In conformity with the structure of the mouth, this species lives entirely by browsing on grass, and is therefore more partial to open countries or districts where there are broad grassy valleys between the tracts of bush.

Such changes are so rapid and on so vast a scale, and the corroding power of the current on the bank so irresistible, that in Lower Bengal it is considered perilous to build any structure of a large or permanent character on its margin.

The Turks have a number of mosques; there are Greek churches and a Jewish synagogue; an old Venetian structure serves as a military hospital; and the prison is of substantial construction.

It is sometimes called the palace quarter, from the royal palace erected between 1868 and 1870, on the site of the older structure dating from the time of Tsaritsa Elizabeth.

St Peter's (Roman Catholic) cathedral (begun 1839, consecrated 1844), Grecian in style, is a fine structure, with a graceful stone spire 224 ft.

The Soldiers', Sailors' and Pioneers' building (1907) is a beautiful structure, classic in design.

Cleavage is thus a superinduced structure, and its explanation is to be found in the rearrangement of the minerals, and the development of a certain degree of crystallization by pressure acting on the rock.

This structure is by no means confined to slates, though always best exemplified in them, owing probably to the finegrained, argillaceous materials of which they consist.

A structure akin to cleavage, often exemplified by slates especially when they have been somewhat contorted or gnarled, is the Ausweichungsclivage of Albert Heim.

In the neighbourhood of intrusive granites and similar plutonic igneous rocks, slates undergo "contact alteration," and great changes ensue in their appearance, structure and mineral composition.

The parish church of All Saints was for the most part rebuilt in the latter half of the 18th century; the portions still preserved of the original structure are mainly Early English.

The church of the Holy Trinity, a fine cruciform structure in the Early Decorated style, was erected in 1865.

Such veins often attain a thickness of several feet, and sometimes possess a columnar structure perpendicular to the enclosing walls; they are met with in the crystalline limestones and other Laurentian rocks of New York and Canada, in the gneisses of the Austrian Alps and the granulites of Ceylon.

Wood charcoal is a hard and brittle black substance, which retains the external structure of the wood from which it is made.

The most interesting churches are those of St Mary and of St Blasius, dating respectively from the 14th and the 12th century; the town-hall is also a fine medieval structure.

In Leydigia he has recently found a structure almost as complex as that of the Daphniidae.

By various modifications of their valves and appendages the creatures have become adapted for swimming, creeping, burrowing, or climbing, some of them combining two or more of these activities, for which their structure seems at the first glance little adapted.

They resemble the latter in the elongation of the body, the large number of vertebrae (240 in Gymnotus), and the absence of pelvic fins; but they differ in all the more important characters of internal structure.

Such an agreement in the structure of so complicated and specialized an apparatus can only be the result of a community of descent of the families possessing it.

Sometimes, for instance, the excerpts from the older documents form long and complete narratives; in other cases (as in the account of the Flood) they consist of a number of short passages, taken alternately from two older narratives, and dovetailed together to make a continuous story; in the books of Judges and Kings the compiler has fitted together a series of older narratives in a framework supplied by himself; the Pentateuch and book of Joshua (which form a literary whole, and are now often spoken of together as the Hexateuch) have passed through more stages than the books just mentioned, and their literary structure is more complex.

Judges, Samuel and Kings.-The structure of these books is simpler than that of the Hexateuch.

The books of Ezra and Nehemiah are of similar structure; here the sources excerpted are the Memoirs of Ezra.

At this point the Maas is crossed by a bridge erected in 1866-67, and the Roer by one dating from 1771, replacing an older structure, and connecting Roermond with the suburb of St Jacob.

Besides those already mentioned, his works include An Outline of the First Principles of Horticulture (1832), An Outline of the Structure and Physiology of Plants (1832), A Natural System of Botany (1836), The Fossil Flora of Great Britain (with William Hutton, 1831-1837), Flora Medica (1838), Theory of Horticulture (1840), The Vegetable Kingdom (1846), Folia Orchidacea (1852), Descriptive Botany (1858).

All Saints' church in South Lynn is a beautiful Decorated cruciform structure.

The so-called Tempio della Tosse, an octagonal domed structure just below the town, is probably a tomb of the 4th century A.D.

He has observed that in young specimens of Siren lacertina (the larva is still unknown) the gills are rudimentary and functionless, and that it is only in large adult specimens that they are fully developed in structure and function; he therefore concludes that the sirens are the descendants of a terrestrial type of batrachians, which passed through a metamorphosis like the other members of their class, but that more recently they have adopted a permanently aquatic life, and have resumed their branchiae by reversion.

In adaptation to these varied surroundings they exhibit great variety in shape, size and structure.

In their general structure the Iguanidae closely resemble the Agamidae, from which they differ mainly by the pleurodont dentition.

Different erroneous assignments of the form have been made even by recent authors, who neglected the clear evidence afforded by the internal structure of the Pratincole.

Betel nuts have been used by turners for ornamental purposes, and for coat buttons on account of the beauty of their structure.

Both as regards structure and habits, the leopard may be reckoned as one of the more typical representatives of the genus Felis, belonging to that section in which the hyoid bone is loosely connected with the skull, owing to imperfect ossification of its anterior arch, and the pupil of the eye when contracted under the influence of light is circular, not linear as in the smaller cats.

In this connexion he developed his special theory of saltations, or of sudden modifications of structure through changes of environment, especially through the direct influences of temperature and atmosphere.

Able as von Meyer was, his classification of the Reptilia failed because based upon the single adaptive characters of foot structure.

The external similarity in the fore paddle and back fin of these three marine animals is absolute, although they are totally unrelated to each other, and have a totally different internal or skeletal structure.

For example, among the land vertebrates the feet (associated with the structure of the limbs and trunk) may take one of many lines of adaptation to different media or habitat, either aquatic, terrestrial, arboreal or aerial; while the teeth (associated with the structure of the skull and jaws) also may take one of many lines of adaptation to different kinds of food, whether herbivorous, insectivorous or carnivorous.

This independence of adaptation applies to every detail of structure; the six cusps of a grinding tooth may all evolve alike, or each may evolve independently and differently.

A very important evolutionary principle is that in such secondary returns to primary phases lost organs are never recovered, but new organs are acquired; hence the force of Dollo's dictum that evolution is irreversible from the point of view of structure, while frequently reversible, or recurrent, in point of view of the conditions of environment and adaptation.

Nature, limited in her resources for adaptation, fashioned so many of these animals in like form that we have learned only recently to distinguish similarities cf analogous habit from the similitudes of real kinship. From whatever order of Mammalia or Reptilia an animal may be derived, prolonged aquatic adaptation will model its outer, and finally its inner, structure according to certain advantageous designs.

Great waves of extinction have followed the long periods of the slow evolution of relatively inadaptive types of tooth and foot structure, as first demonstrated by Waldemar Kowalevsky; thus mammals are repeatedly observed in a cul-de-sac of structure from which there is no escape in an adaptive direction.

Ehrenberg's monograph, which contained a mass of detail regarding their structure.

From these are given off at irregular intervals short lateral branches, each of which terminates in a flame-cell (f) precisely similar in structure to the flame-cells found in Planarians, Trematodes and Cestodes; here as there the question whether they are open to the body cavity or not must probably be answered in the negative.

Additional paired antennae may occur within the coronal surface, which is the seat of the sensory styles, of less complex structure, which occur in many genera.