CONCLUDING REMARKS 217 



The herbivorous stage was followed by an omnivorous one, 

 characterised by the development of powerful canines. In this 

 way, as skill in hunting and slaying animals developed, and 

 carnivorous diet became of continually greater importance, the 

 intestinal tube would appear to have begun to shorten and the 

 processus vermiformis to become constricted. 



Laryngeal sinuses may have been developed, which, acting as 

 resonators, lent the voice greater strength and carried it farther, 

 and thus made it a means of frightening or enticing. The 

 lower jaw, the neck and its musculature, were far more powerfully 

 developed than now. 



In the male the genital glands may have remained, as they 

 now normally do in the female, within the abdominal cavity, 

 and been thus better protected from injury than at present. At 

 a later stage even, when they had changed their position, and had 

 reached the pouch-like appendages of the abdominal integument, 

 they could still be withdrawn into the cavum abdominis, at least 

 temporarily, by means of a well-developed muscle (cremaster). 

 This is still indicated by ontogenetic processes. 



There can be no doubt that the ancestors of Man were pro- 

 vided with a more extensive mammary system and more numerous 

 mammae than he to-day possesses, and the significance of this fact 

 is equally clear. It can only be explained by the assumption that 

 a greater number of young were originally produced at a birth. 

 This, of course, was of advantage in the preservation of the species. 



It follows from the above that in the course -of a long 

 geological period, Man has gradually lost a great number of 

 advantages once possessed by his ancestors, and the question 

 arises whether he has acquired any others in exchange for those 

 lost. This certainly is the case, and this indeed must have 

 been so, otherwise the species Homo would have failed in the 

 struggle for existence. We thus have a series of exchanges, based 

 (if we take only the most important organ into consideration) 

 upon the unlimited capacity of development of the human brain. 

 This one acquisition, supported by an increased functional 

 efficiency of the hand and by the development of articulate speech, 

 has entirely compensated for the loss of the great series of ad- 

 vantageous arrangements mentioned above. They had to be 

 sacrificed in order that the brain might successfully develop, and 

 that the Homo sapiens of to-day, with his surprising adaptability 

 to the most varied conditions of life, might be produced. 



This momentous exchange took place slowly and only after 



