10 THE DESCENT OF MAN. 



"quite in the later stages of development that the young 

 human being presents marked differences from the young 

 ape, while the latter departs as much from the dog in its 

 developments as the man does. Startling as this last asser- 

 tion may appear to be, it is demonstrably true/' 



As some of my readers may never have seen a drawing of 

 an embryo, I have given one of man and another of a dog, 

 at about the same early stage of development, carefully 

 copied from two works of undoubted accuracy,* 



After the foregoing statements made by such high 

 authorities, it would be superfluous on my part to give a 

 number of borrowed details, showing that the embryo of 

 man closely resembles that of other mammals. It may, 

 however, be added, that the human embryo likewise resem- 

 bles certain low forms when adult in various points of 

 structure. For instance, the heart at first exists as a simple 

 pulsating vessel ; the excreta are voided through a cloacal 

 passage ; and the os coccyx projects like a true tail, " ex- 

 tending considerably beyond the rudimentary legs."f In 

 the embryos of all air-breathing vertebrates, certain glands, 

 called the corpora Wolffiana, correspond with, and act 

 like the kidneys of mature fishes. J Even at a later 

 embryonic period, some striking resemblances between 

 man and the lower animals may be observed. Bischoif 

 says that " the convolutions of the brain in a human foetus 

 at the end of the seventh month reach about the same 

 stage of development as in a baboon when adult. " 

 The great toe, -as Prof. Owen remarks, | " which forms 

 the fulcrum when standing or walking, is perhaps 



*The human embryo (upper fig.) is from Ecker, " Icones Phys.," 

 1851-1859, tab. xxx, fig. 2. This embryo was ten lines in length, so 

 that the drawing is much magnified. The embryo of the dog is from 

 Bischoff, " Entwicklungsgeschichte des Hunde-Eies," 1845, tab. xi, 

 fig. 42 B. This drawing is five times magnified, the embryo being 

 twenty five days old. The internal viscer; have been omitted, and 

 the uterine appendages in both drawings removed. I was directed 

 to these figures by Prof. Huxley, from whose work, " Man's Place in 

 Nature," the idea of giving them was taken. Hackel has also given 

 analogous drawings in his " Schopfungsgeschichte." 



f Prof. Wyinan in " Proc. of American Acad. of Sciences." vol. iv. 

 1860, p. 17. 



% Owen, " Anatomy of Vertebrates," vol. i, p. 533. 



" Die Grosshirnwindungen des Menschen," 1868, s. 95. 



| " Anatomy of Vertebrates," vol. ii, p. 553. 



