General Outline of the Organisation of the Animal Kingdom: And Manual of Comparative Anatomy

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J. Van Voorst, 1855 - 842 Seiten
 

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Seite 644 - The eye itself differs in many points of structure from that of terrestrial Vertebrata, its organization being of course adapted to bring the rays of light to a focus upon the retina in the denser element in which the fish resides ; the power of the crystalline lens is therefore increased to the utmost extent, and the antero-posterior diameter of the eye-ball necessarily contracted in the same ratio, in order that the retina may be placed exactly in the extremely short focus of the powerful lens.
Seite 382 - The process was described for its better intelligibility in the Aphides as one of a simple succession of single individuals, but it is much more marvellous in nature. The firstformed larva of early spring procreates not one but eight larvae like...
Seite 218 - ... structure of the penis. The result of our own examination, in more than one species, is different still. We have always found the earthy matter forming a jointed calcareous tube. This tube, which is about the thickness of a surgeon's probe, is composed of rings of calcareous substance connected by membrane, so that viewed externally it is not unlike the windpipe of a small animal.
Seite 789 - ... with each other. The medulla spinalis is surrounded with a network of arteries in the same manner, more especially where it comes out from the brain, where a thick substance is formed by their ramifications and convolutions ; and these vessels most probably anastomose with those of the thorax.
Seite 561 - ... took one the day after the first experiment, and found that the aperture was covered by a thin glutinous lamina, which, somewhat in the manner of a cobweb, unites the two margins of the broken shell. The next day the lamina was, to a certain degree, thickened and more opaque, till, at the expiration of ten or twelve days, the new piece had become quite calcareous. Whilst the Argonaut was in the act of mending the fractures in its shell, I am quite sure that it applied the sails to the shell and...
Seite 272 - The attenuated rings in the neighbourhood of the mouth are first insinuated between the particles of the earth, which, from their conical shape, they penetrate like a sharp wedge ; in this position they are firmly retained by the numerous recurved spines appended to the different segments ; the hinder parts of the body are then drawn forward by a longitudinal contraction of the whole animal — a movement which not only prepares the creature for advancing further into the soil, but by swelling out...
Seite 789 - Thus the heart and aorta of the Spermaceti Whale appeared prodigious, being too large to be contained in a wide tub, the aorta measuring a foot in diameter. When we consider these as applied to the circulation, and figure to ourselves that probably ten or fifteen gallons of blood are thrown out at one stroke, and moved with an immense velocity through a tube of a foot in diameter, the whole idea fills the mind with wonder.
Seite 379 - Reaumur has proved that in five generations one Aphis may be the progenitor of 5,904,900,000 (billions) descendants; and it is supposed that in one year there may be 20 generations...
Seite 444 - The poor beetle, which we tread upon, In corporal sufferance feels a pang as great As when a giant dies.
Seite 388 - ... temple like the blinders of a horse ; and next, having by means of the joint at your chin let down the whole apparatus and uncovered your face, employ them in seizing any food that presented itself, and conveying it to your mouth. Yet this procedure is that adopted by the larvae provided with this strange organ.

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