. A text-book of comparative physiology [microform] : for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. 669 COMPARATIVE forms the tapetum. It is most pronounced in the carnivom and givee the glare to their eyee aa well Been in the oat tribe at night It has been supposed to act as a reflector and thus assist in vision in the same way as a pair of carriage lamps light up the roadway. Bvolnliai.âFrom the above brief aocQunt of the eye in dif- ferent grades of animals,
. A text-book of comparative physiology [microform] : for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. 669 COMPARATIVE forms the tapetum. It is most pronounced in the carnivom and givee the glare to their eyee aa well Been in the oat tribe at night It has been supposed to act as a reflector and thus assist in vision in the same way as a pair of carriage lamps light up the roadway. Bvolnliai.âFrom the above brief aocQunt of the eye in dif- ferent grades of animals, it will ap- pear that its modifications answer to differences in the environment Adaptation is evident Darwin believes this to have been efTeoted partly by natural selectionâi. e., the â urvival of the animal in which the form of eye appeared best adapted to its needsâand partly by the use or disuse of certain parts. The latter is illustrated by the blind fishes, insects, etc., of certain caves, a' those of Kentucky; and it Fi« wo-Bye of Boctamai bird is of extreme interest to note that i?«'M?ir»; various grades of IransitiontoWMd ; ;^, complete blindneds are observable, ^cmi"^' according to the degree of darkness Hf'iKm&o'CK: in which the animal Uves, whether trerne mobility of the iru. wholly within the cave or where there is still some light A crab has been found witfi the eye- stalk still present, but th« eye itself atrophied. Again, ani- mals that burrow seem to be in process of losing their eyes, through inflammation from obvious causes; and some of them, as the moles, have the eye stiU existing, tiiough wdl-nigh or wholly covered with skin. Internal parasites are often witii- out eyes. It is not difficult to understand how one bu^ of prey, with eves superior to tiiose of xi» fellows, would giun supremacy, and, i^ periods of scarcity, survive and leave offspnng when others would perish. v v-i. « I
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