10 THE DESCENT OF MAN. 



"quite in the later stages of development that the yonng 

 human l)eing })resents 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 sjime 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 I^ 

 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. Bischoff 

 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 abryo (upper fig.) is from Ecker, " I cones 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, " 'ntwicklungsgeschichte des Hunde-Eies," 1845, tab. xi, 

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

 twenty-five days old. The internal viscera ave 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 ** Schfipfungsgeschichte." 



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

 1860, p. 17. 



JOwen, "Anatomy of Vertebrates," vol. i, p. 533. 



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



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



