1B6 THE DESCENT OP MAN. 



We have thus far endeavored rudely to trace the genealogy 

 of the Vertehrata by the aid of their mutual affinities. We will 

 noY/ look to man as he exists; and we shall, 1 think, be able 

 partially to restore the structure of our early progenitors, during 

 successive periods, but not in due order of time. This can be 

 effected by means of the rudiments which man still retains, by 

 the characters which occasionally make their appearance in him 

 through reversion, and by the aid of the principles of morphology 

 and embryology. The various facts, to which I shall here allude, 

 have been given in the previous chapters. 



The early progenitors of man must have been once covered 

 with hair, both sexes having beards; their ears were probably 

 pointed, and capable of movement; and their bodies were pro- 

 vided with a tail, having the proper muscles. Their limbs and 

 bodies were also acted on by many muscles which now only 

 occasionally reappear, but are normally present in the Quadru- 

 mana. At this or some earlier period, the great artery and nerve 

 of the humerus ran through a supra-condyloid foramen. The 

 Intestine gave forth a much larger diverticulum or caBcum than 

 that now existing. The foot was then prehensile, judging from 

 the condition of the great toe in the foetus; and our progenitors, 

 no doubt, were arboreal in their habits, and frequented some 

 warm, forest-clad land. The males had great canine teeth, which 

 served them as formidable weapons. At a much earlier period 

 the uterus was double; the excreta were voided through a cloaca; 

 and the eye was protected by a third eyelid or nictitating mem- 

 brane. At a still earlier period the progenitors of man must have 

 been aquatic in their habits; for morphology plainly tells us that 

 our lungs consist of a modified swim-bladder, which once served 

 as a float. The clefts on the neck in the embryo of man show 

 where the branchiae once existed. In the lunar or weekly re- 

 current periods of some of our functions we apparently still retain 

 traces of our primordial birthplace, a shore washed by the tides. 

 At about this same early period the true kidneys were replaced 

 by the corpora wolffiana. The heart existed as a simple pulsating 

 vessel; and the chorda dorsalis took the place of a vertebral 

 column. These early ancestors of man, thus seen in the dim 

 recesses of time, must have been as simply, or even still more 

 simply organized than the lancelet or amphioxus. 



There is one other point deserving a fuller notice. It has long 

 been known that in the vertebrate kingdom one sex bears rudi- 

 ments of various accessory parts, appertaining to the reproduc- 

 tive system, which properly belong to the opposite sex; and it 

 has now been ascertained that at a very early embryonic period 

 both sexes possess true male and female glands. Hence some re- 

 mote progenitor of the whole vertebrate kingdom appears to have 



