Anatomy of the invertebrata, Volume 1; Volume 1854

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Gould and Lincoln, 1854 - Anatomy, Comparative - 470 pages
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Page 474 - Aphides cannot be said to constitute as many true generations, any more than the different branches of a tree can be said to constitute as many trees ; on the other hand, the whole suite, from the first to the last, constitute but a single true generation.
Page 15 - The invertebrate animals are organized after various types, the limits of which are not always clearly defined. There is, therefore, a greater number of classes among them than among the vertebrates. But, as the details of their organization are yet but imperfectly known, they have not been satisfactorily classified in a natural manner. There are among them many intermediate forms, which make it difficult to decide upon the exact limits of various groups. The following division, however, from the...
Page 473 - From this last-mentioned fact, it is evident that, even admitting that these germ-masses are true eggs, the conditions of development are quite different from those of the eggs of the truly viviparous animals, for in these last the egg is merely hatched in the body instead of out of it, and, moreover, it is...
Page 474 - This germ-power may be extended by gemmation or by fission, but it can be formed only by the act of generation, and its play of extension and prolongation by budding, or by division, must always be within a certain cycle...
Page 473 - Insecta, are not continuous with any uterine or other female organ, and therefore do not at all communicate with the external world; on the other hand, they are simply attached to the inner surface of the animal, and their component germs are detached into the abdominal cavity as fast as they are developed, and thence escape outwards through a porus genitalis.
Page vii - In the text will be found a lucid yet succinct exposition of the anatomical structure of organs, arranged as far as practicable under distinct types. The details on which this typical summary is based, are comprised in notes which are as remarkable for their erudition as for their copiousness ; indeed, the utmost care has been taken in the literature of the various subjects treated, and the student will here find the most reliable and at the same time the fullest reference to the bibliography of...
Page 473 - During this time, the yellowish, vitellus-looking mass has not changed its place, and although it is somewhat increased in size, yet it appears otherwise the same. When the development has proceeded a little further, and the embryo has assumed a pretty definite form, the arches of the segments, which have hitherto remained gapingly open, appear to close together on the dorsal surface, thereby enclosing the vitellus-looking mass within the abdominal cavity.
Page 425 - From the ganglion in question passes off a band of nervous substance which stretches along the slightly excavated anterior side of the trachean vesicle. Upon this band is situated a row of transparent vesicles containing the same kind of cuneiform staff-like bodies, mentioned as occurring with the Acrididze.
Page 32 - Chilodon, the nucleus is sulcated longitudinally or transversely, or even entirely divided, before the surface of the body presents any constriction. This nucleus, which is of a finely granular aspect and dense structure, retains perfectly its form when the animal is pressed between two plates of glass, and the other parts are spread out in various ways. By direct light its color appears pale yellow. It appears to lie very loosely in the parenchyma, and sometimes individuals may be observed turning...
Page 454 - Elateridae, the illumination occurs through two transparent spots situated on the dorsal surface of the prothorax. The light produced by these organs so remarkably rich in tracheae, is undoubtedly the result of a combustion kept up by the oxygen of the air of these vessels.

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