Animal life in the sea and on the land . Fig. 155.—Mouth of the Crocodile. rf, tongue; e, glands; /, inferior, and a, superior, valves separating the cavity ofthe liioiuh from tiie throat, h. 23S ANIMAL LIFE IN THE SEA AND ON THE LAND. 7. The Heart and the Circulation of the Blood. — Wemust not fail to examine the heart of the crocodile, for we shall find in it a decided step in advance of the Otherreptiles. The change which we had reason to expect hasat last taken place. You will remember that we noticedan incomplete partition in the ventricle o( the snake, but. Fiir. 156.—Alligator. here the
Animal life in the sea and on the land . Fig. 155.—Mouth of the Crocodile. rf, tongue; e, glands; /, inferior, and a, superior, valves separating the cavity ofthe liioiuh from tiie throat, h. 23S ANIMAL LIFE IN THE SEA AND ON THE LAND. 7. The Heart and the Circulation of the Blood. — Wemust not fail to examine the heart of the crocodile, for we shall find in it a decided step in advance of the Otherreptiles. The change which we had reason to expect hasat last taken place. You will remember that we noticedan incomplete partition in the ventricle o( the snake, but. Fiir. 156.—Alligator. here there is a perfect partition making two separate ven-tricles, and the heart is thus divided into four distinct pure blood is consequently kept separate from theimpure blood as long as it remains in the heart. 8. The advantage gained by this arrangement is soonlost, however, for the main arteries carrying both the pureand the impure blood unite soon after leaving the heart, CROCODILES. 239 and the two kinds of blood flow together in one mixed blood is therefore sent through the body of thecrocodile, the same as in other cold-blooded animals. Not-withstanding this apparent failure, a perfect circulation, bywhich the system is supplied only with pure blood, is near-ly reached, as we shall find when we come to treat of birds. 9. Alligators. — Alligators are very much like croco-diles, except that they are smaller, that their feet are notso completely webbed, and that they are found only inAmerica. They are very numerous in the rivers andsw
Size: 1873px × 1334px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1887
