DESCENT OF MAN FROM SOME LOWER FORM. 131 



which causes certain normal processes, such as gestation, 

 as well as the maturation and duration of various dis- 

 eases, to follow lunar periods. His wounds are repaired 

 by the same process of healing ; and the stumps left after 

 the amputation of his limbs, especially during an early 

 embryonic period, occasionally possess some power of re- 

 generation, as in the lowest animals. 



Man is developed from an ovule, about the 

 125th of an inch in diameter, which differs in 

 no respect from the ovules of other animals. The embryo 

 itself at a very early period can hardly be distinguished 

 from that of other members of the vertebrate kingdom. 

 At this period the arteries run in arch-like branches, as if 

 to carry the blood to branchiae which are not present in 

 the higher vertebrata, though the slits on the side of the 

 neck still remain, marking their former position. At a 

 somewhat later period, when the extremities are developed, 

 "the feet of lizards and mammals," as the illustrious Von 

 Baer remarks, " the wings and feet of birds, no less than 

 the hands and feet of man, all arise from the same funda- 

 mental form." It is, says Professor Huxley, "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 de- 

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

 tion may appear to be, it is demonstrably true." 



THE FACTS OF EMBRYOLOGY AND THE THEORY OF DE- 

 VELOPMENT. 



Origin of This i g one °f tne mos t important subjects 



Species, (embryology) in the whole round of natural 



history. The metamorphoses of insects, with 



which everyone is familiar, are generally effected abruptly 



