. Biology and its makers : with portraits and other illustrations. Biology -- History. 3^4 BIOLOGY And its makers arteries of the head and the neck undergo great changes long before the chick is hatched. Similar gill-clefts and similar arrangements of blood-vessels appear also very early in the development of the young rabbit, and in the development of all higher life. Except for the theory of descent, such things would remain a lasting enigma. The universal pres- ence of gill-clefts is not to be looked on as a haphazard. Fig. I lo.—The Jaws of an Embryoni-c Whale, Showing Rudimentary Teeth. o
. Biology and its makers : with portraits and other illustrations. Biology -- History. 3^4 BIOLOGY And its makers arteries of the head and the neck undergo great changes long before the chick is hatched. Similar gill-clefts and similar arrangements of blood-vessels appear also very early in the development of the young rabbit, and in the development of all higher life. Except for the theory of descent, such things would remain a lasting enigma. The universal pres- ence of gill-clefts is not to be looked on as a haphazard. Fig. I lo.—The Jaws of an Embryoni-c Whale, Showing Rudimentary Teeth. occurrence. They must have some meaning, and the best suggestion so far offered is that they are survivals inherited from remote ancestors. The higher animals have sprung from simpler ones, and the gill-slits, along with other rudi- mentary organs, have been retained in their history. It is not necessary to assume that thev are inherited from adult ancestors; they are, more likely, embryonic structures still retained in the developmental history of higher Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Locy, William A. (William Albert), 1857-1924. New York : Henry Holt
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyorkhenryholt
