This system of channels is in communication with the outer atmosphere through numerous small apertures, known as stomata, which are abundant upon the leaves and young twigs, and gaseous interchange between the plant and the air is by their assistance rendered constant and safe.
This power of varying the area of the apertures by which gases enter the internal reservoirs is not advantageous to the gaseous interchangesindeed it may be directly the reverse.
Most of these extend through narrow apertures foramina pneumatica - into the hollow bones, sometimes, e.g.
It has been asserted (and denied) that the cellular rod which is known as the "Heart-body" (Herzkorper), and is to be found in the dorsal vessel of many Oligochaeta and Polychaeta, is formed of cells which are continuous with the chloragogen cells, thus implying the existence of apertures of communication with the coelom.
Segments are the apertures of the Nervous system rarely atria.C, Perichaeta: the spermathecal pores (Aeolosoma) in continuity are between segments 6 and 7, 7 with epidermis.
17, d), we find right and left of the two renal apertures a right and left gillplume or ctenidium, which here as in Haliotis and Pleurotornaria retain their original paired condition.
A further degree of modification occurs when the male duct takes its origin from the hermaphrodite duct above the external opening, so that there are two distinct apertures, one male and one female, the latter being the original opening.
39, and the various apertures of the body are seen.
The Eolid-like Nudibranchs, amongst other specialities of structure, possess (in some cases at any rate) apertures at the apices of the " cerata " or dorsal papillae, which lead from the exterior into the hepatic caeca.
Genital duct diaulic, without open seminal groove; male and female apertures contiguous.
Genital duct diaulic; male and female apertures contiguous.
Genital duct diaulic; male and female apertures contiguous.
Dorsal papillae with a membranous expansion; male and female apertures at some distance from each other; pelagic. Fiona.
Genital duct always triaulic, and male and female apertures distant from each other.
Visceral mass and shell conical; tentacles atrophied; head expanded; genital apertures contiguous; marine animals, with an aquatic pallial cavity containing secondary branchial laminae.
Visceral mass and shell conical; head flattened; pallial cavity aquatic, but without a branchia; genital apertures separated.
Male and female genital apertures open into a common vestibule, except in Vaginulidae and Oncidiidae.
No shell, a carinated mantle covering the whole body; male and female apertures distant, the female near the anus.
Anterior tentacles much reduced; male and female apertures contiguous but distinct; shell thin,.
The Dipylon consists of an outer and an inner gate separated by an oblong courtyard and flanked on either side by towers; the gates were themselves double, being each composed of two apertures intended for the incoming and outgoing traffic. An opening in the city wall a little to the south-west, supposed to have been the Sacred Gate (iep t riAn), was in all probability an outlet for the waters of the Eridanus.
Narrow apertures between adjoining galleries.
Nasal apertures very large, and extending high on the face between the orbits; nasal bones short, elevated, triangular and pointed in front.
The genital apertures are placed in the first somite following the prosoma, excepting where a praegenital somite, usually suppressed, is retained.
2, Second opisthosomatic sternite covering the second pair of tracheal apertures sp I .
The confluence of the regions of the body and the dislocation of apertures from their typical position are results of degeneration.
When, as in the application to rectangular or circular apertures, the form is symmetrical with respect to the axes both of x and y, S = o, and C reduces to C = ff cos px cos gy dx dy,.
The results of the theory of the diffraction patterns due to circular apertures admit of an interesting application to coronas, such as are often seen encircling the sun and moon.
If we take a direction such that the light (of given wave-length) from a single aperture vanishes, the evanescence continues even when the whole series of apertures is brought into contemplation.
The light stopped by the opaque parts of the grating, together with that distributed in the central image and lateral spectra, ought to make up the brightness that would be found in the central image, were all the apertures transparent.
2s = 277-h/A f (14) e = Af /h (15) The bands are thus of the same width as those due to two infinitely narrow apertures coincident with the central lines of the retarded and unretarded streams, the subject of examination being itself a fine luminous line.
The glass in process of fusion is contained in a basin or tank built up of large blocks of fire-clay and is heated by one or more powerful gas flames which enter the upper part of the furnace chamber through suitable apertures or " ports."
Outline of the ventral surface to show the external apertures and nervous system; a, rosette-organ; b, uterine pore; c, terminal sucker; e, vaginal pore; g, male gonopore; n, o, p, nervous system.
In them a ventral surface containing the usually median male and female genital apertures is generally distinguishable from the smooth FIG.
In southern climes, where during the summer heat it is usual to close the rooms from the glare of the sunshine outside, we may often see depicted on the walls vivid inverted images of outside objects formed by the light reflected from them passing through chinks or small apertures in doors or window-shutters.
He seems to have been well acquainted with the projection of images of objects through small apertures, and to have been the first to show that the arrival of the image of an object at the concave surface of the common nerve - or the retina - corresponds with the passage of light from an object through an aperture in a darkened place, from which it falls upon a surface facing the aperture.
About the same time Francesco Maurolico, or Maurolycus, the eminent mathematician of Messina, in his Theore y nata de Lumine et Umbra, written in 1521, fully investigated the optical problems connected with vision and the passage of rays of light through small apertures with and without lenses, and made great advances in this direction over his predecessors.
The first to take up the camera obscura after Porta was Kepler, who used it in the old way for solar observations in 1600, and in his Ad Vitellionem Paralipomena (1604) discusses the early problems of the passages of light through small apertures, and the rationale of the simple dark chamber.
4 B, v), but the two apertures may run into one, and may also open dorsally (Hexacotyle).
If ectoparasitic and attached to the skin, apertures or gills, the Trematode adopts more elaborate adhesive organs and undergoes a less complex development than are required for the endoparasitic members of the class.
" the introduction of a diaphragm having two circular apertures touching each other in a point coinciding with the line of collimation of the telescope, and the diameter of each aperture exactly equal to the semidiameter of the cone of rays at the distance of the diaphragm from the focal point of the object-glass."
In addition, numerous other researches stand to Joule's credit - the work done in compressing gases and the thermal changes they undergo when forced under pressure through small apertures (with Lord Kelvin), the change of volume on solution, the change of temperature produced by the longitudinal extension and compression of solids, &c. It was during the experiments involved by the first of these inquiries that Joule was incidentally led to appreciate the value of surface condensation in increasing the efficiency of the steam engine.
There is also a postern gate on the north side of the wall, and at its eastern extremity are two apertures in the thickness of the wall.
The edges of the mantle are united posteriorly except at the anal and branchial apertures, which are placed at the ends of two very short siphons or tubular prolongations of the mantle; the siphons bear a number of short tentacles, and many of these are furnished with eye-spots.
Some of this light also passed through the second hole, and thus he obtained a narrow beam of practically homogeneous light in a fixed direction (the line joining the apertures in the two screens).
A pair of genital apertures, connected by genital ducts with the paired gonads, are found right and left near the nephridial pores, except in a few cases where the genital duct joins that of the renal organ (Spondylus).
When the edges of the mantle ventral to the inhalant orifice are united, an anterior aperture is left for the protrusion of the foot, and thus there are three pallial apertures altogether, and species in this condition are called " Tripora."
In Mytilus the foot is reduced to little more than a tubercle carrying the apertures of these glands.
Male and female apertures distant.
The position of the genital apertures is not known.
In the same figure the free part of the inner lamella of the inner gill-plate resting on the foot is marked z, whilst the attached parjt - the most anterior - has been snipped with scissors so as to show the genital and nephridial apertures x and y.
The pair of renal organs of Anodonta, called in Lamellibranchs the organs of Bojanus, lie below the membranous floor of the pericardium, and open into it by two well-marked apertures (e and f in fig.
Hence, except for the formation of a urino-genital groove, the apertures are placed as they are in Anodonta.
In Mytilus the two apertures are on a common papilla, in other cases the two apertures are as in Anodonta.
The Anatinacea and Poromya among the Septibranchia are, however, peculiar in having two genital apertures on each side, one male and one female.
Renal and genital apertures separate.
Tridacnidae.-Mantle closed to a considerable extent; apertures distant from each other; no siphons; a single adductor; shell thick.
At this time, however, the flesh was replaced by a stuffing of sawdust, sand, or other lasting material, introduced with great skill through a few incisions and apertures, so that the natural forms were completely restored.