1) as dorsal outgrowths of the collar.
In some hydroids the founder-polyp, developed from a planula after fixation, throws out numerous outgrowths from the base to form the hydrorhiza; these outgrowths may be radially arranged so as to form by contact or coalescence a flat plate.
It would be necessary to regard this structure as a secondary extension of the endoderm in the tentacle-web, on Allman's theory, or between the outgrowths of the hydrorhiza, on Mechnikov's hypothesis.
Eight very broad radial canals; ex-umbrella often provided with lateral outgrowths; tentacles differing in size, but in a single row.
Phytophthora in potatoes., If, on the other hand, the irritating agent is local in its action, causing only a few cells to react, we have the various pimples, excrescences, outgrowths, &c., exhibited in such cases as Ustilago Maydis on the maize, various galls, witchesbrooms, &c.
Excrescences.Outgrowths, more or less abnormal in character, are frequent signs of diseased organs.
The injury which initiates them may be very slight in the first placea mere abrasion, puncture or Fungus infectionbut the minute wound or other disturbance, instead of healing over normally, is frequently maintained as a perennial source of irritation, and the regenerative tissues grow on month after month or year after year, resulting in extraordinary outgrowths often of large size and remarkable shape.
There is a class of gall-like or pustular outgrowths for which no external cause has as yet been determined, and which are therefore often ascribed to internal causes of disease.
Such are the cork-warts on elms, maples, &c., and the class of outgrowths known as Intumescences.
Turning now to outgrowths of a woody nature, the well-known burrs or knaurs, so common on elms and other trees are cases in point.
There are many Varieties of burrs, though all woody outgrowths of old trees are not to be confounded with them, e.g.
Other common modifications arise from the union of certain parts of the perianth to each other, and from the varied and often very remarkable outgrowths from the lip. These modifications are associated with the structure and habits of insects and their visits to the flowers.
In other Polychaetes one or more pairs of similar outgrowths are glandular.
The Oligochaeta contrast with the Polychaeta in the general presence of outgrowths of the septa in the genital segments, which are either close to, or actually involve, the gonads, and into which may also open the funnels of the gonad ducts.
It was in the year 1886 that Hellriegel and Wilfarth first published in Germany the results of investigations in which they demonstrated that, through the agency of micro-organisms dwelling in nodular outgrowths on the roots of ordinary leguminous plants, the latter are enabled to assimilate the free nitrogen of the air.
The sucker-bearing processes of Pneumonoderma are outgrowths of the proboscis.
As in some Pectinibranchia, the free margin of the mantle-skirt is frequently reflected over the shell when a shell exists; and, as in some Pectinibranchia, broad lateral outgrowths of the foot (parapodia) are often developed which may be thrown over the shell or naked dorsal surface of the body.
The possession of a variable number of excretory tubes (Malpighian tubes), which are developed as outgrowths of the hind-gut and pour their excretion into the intestine,is also a distinctive character of the Hexapoda.
In addition to the wings there are smaller dorsal outgrowths of the thorax in many insects.
Hexapoda with this resting pupal stage in their life-history are said to undergo " a complete transformation," to be metabolic, or holometabolic, whereas those insects in which the young form resembles the parent are said to be ametabolic. Such insects as dragon-flies and may-flies, whose young, though unlike the parent, develop into the adult form without a resting pupal stage are said to undergo an " incomplete transformation " or to be hemimetabolic. The absence of the pupal stage depends upon the fact that in the ametabolic and hemimetabolic Hexapoda the wing-rudiments appear as lateral outgrowths (fig.
A remarkable fossil from the Scottish Coal-measures (Lithomantis) had apparently small wing-like structures on the prothorax, and in allied genera small veined outgrowths - like tracheal gills - occurred on the abdominal segments.
Insect wings are specialized outgrowths of certain thoracic segments, and are quite unrepresented in any other class of Arthropods.
Comparison of the tracheated wings with the paired tracheated outgrowths on the abdominal segments of the aquatic campodeiform larva of may-flies (see fig.
The origin of insect wings remains, therefore, a mystery, deepened by the difficulty of imagining any probable use for thoracic outgrowths, comparable to the wingrudiments of the Exopterygota, in the early stages of their evolution.
In its simplest form this is a hollow flask-shaped horny piece, consisting of a dilated basal portion and a terminal spiniform portion with an orifice at the apex; but its structure is frequently complicated by accessory processes and outgrowths which aid copulation and serve to protect the delicate point from injury.
Two lateral outgrowths of the foremost portion of the oesophagus, afterwards becoming constricted off, as well as two ingrowths from the epiblast, contribute towards its formation, at least as far as both Metaand Heteronemertines are concerned.
No other intermediate stages have as yet been noticed between this arrangement and that of the Heteronemertini, in which a separate posterior brain-lobe receives a similar ciliated canal, and in which the oesophageal outgrowths have made their appearance and are coalesced with the nerve-tissue in the organ of the adult animal.
These posterior brain-lobes, which in all Heteronemertines are in direct continuity of tissue with the upper pair of principal lobes, cease to have this intimate connexion in the Metanemertini; and, although still constituted of (I) a ciliated duct, opening out externally, (2) nervous tissue surrounding it, and (3) histological elements distinctly different from the nervous, and most probably directly derived from the oesophageal outgrowths, they are nevertheless here no longer constantly situated behind the upper brain-lobes and directly connected with them, but are found sometimes behind, sometimes beside and sometimes before the brain-lobes.
Thus in borage it is rotate, tubular in comfrey, funnel-shaped in hounds-tongue, and salvershaped in alkanet (Anchusa); the throat is often closed by scale-like outgrowths from the corolla, forming the so-called corona.
In the case of the peach this peculiarity is in some way connected with the presence of small glandular outgrowths on the stalk, or at the base of the leaf.
In one family, the Ptychoderidae, the medullary tube of the collar is connected at intermediate points with the epidermis by means of a variable number of unpaired outgrowths from its dorsal wall, generally containing an axial lumen derived from and in continuity with the central canal.
These bodies had been erroneously supposed by Newport (12) and other observers to be glandular outgrowths of the alimentary canal.
In length and i in breadth, with a pair of tendinous outgrowths standing out from it at right angles on each side.
3 and 4) the entosternite has tough membrane - like outgrowths or genital somite.
I and 2) correspond in the two animals, and the median lateral process imp of the scorpion represents the tendinous outgrowths ALR, PLR of Limulus.
The scorpion's entosternite gives rise to outgrowths, besides the great posterior flaps, pf, which form the diaphragm, unrepresented in Limulus.
The only point in which the gut of Limulus resembles that of Scorpio rather than that of any of the Crustacea, is in possessing more than a single pair of ducts or lateral outgrowths connected with ramified gastric glands or gastric caeca.
C. Its four transverse lobes or outgrowths corresponding to the four coxae.
The great development of all branches of mathematics in the two centuries following Descartes has led to the term algebra being used to cover a great variety of subjects, many of which are really only ramifications of arithmetic, dealt with by algebraical methods, while others, such as the theory of numbers and the general theory of series, are outgrowths of the application of algebra to arithmetic, which involve such special ideas that they must properly be regarded as distinct subjects.
It bears adhesive organs that are either suckers or hooks, and may develop into the most varied outgrowths in order to give increased firmness of attachment to its host.
C q t;: pm .-..,,?i are transferred into two tubes (Solenophoridae); and by the closure of the lower aperture reconstituted into two suckers, the margins of which are produced and folded so as to resemble the leaf-like outgrowths of the next group. In this division (Tetraphyllidea) four suckers or bothria are developed on the scolex, but their cavities are extremely shallow and their lips extremely mobile and variable in shape.
Scolex with four outgrowths forming organs of adhesion and probably also of locomotion.
Round the blastopore hollow outgrowths, variable in number, arise by the evagination of the entire body-wall, both ectoderm and endoderm.
A pair of large glandular outgrowths, the so-called " liver " or great digestive gland, exists as in other Molluscs.
Complications follow upon this in other forms. Even in Mytilus and Arca a connexion is here and there formed between the ascending and descending rami of a filament by hollow extensible outgrowths called " interlamellar junctions " (il.
Hagen observed that some genera possess wing-like outgrowths on the prothorax, comparable to those seen in certain insects of the Carboniferous Period.
The renal organs are tubular outgrowths of the pericardial parts of the coelom; the reproductive cells are derived from cells lining the generative portion.
They arise as outgrowths of the sides of the body within the cavity formed by the development of the mantle.
Outgrowths of the foot.
In Dacryomyces only two outgrowths and two spores are produced.