1 84 EVOLUTION AND SOCIAL PROGRESS 



the jaw. Many similar cases could be cited, which 

 seem to furnish a very strong argument for the 

 relationship of certain groups of animals, and for 

 their probable descent from certain ancestral 

 types. Concerning man, what evidence can be 

 drawn from this line of thought as to his descent 

 from the ape ? 



The answer is simple; none whatsoever! In 

 the first place, many of the organs once thought 

 to be vestigial or rudimentary are now known to 

 exercise very definite and important functions of 

 which scientists had been ignorant before. Spe- 

 cific instances mentioned by Wasmann are: the 

 thymus gland, now known to eliminate poisonous 

 matter from the system, and the pineal gland, 

 once actually taken to be the remnant of a third 

 eye possessed by some brute progenitor, until 

 Cyon made known its function as a regulator of 

 the flow 'of blood at the base of the brain. So 

 too in the case of the thyroid gland. 8 



A second explanation applicable in some in- 

 stances is, that organs are apt to fall into disuse 

 owing to changed conditions of living. Thus the 

 ear and face muscles of man, now useless, may 

 have been more developed at some early period, 

 and have degenerated later. As regards the ver- 

 miform appendix, particularly referred to by 

 Darwin and his earlier followers, its peculiar 

 pathological character might easily be due to 



8 Cf. ibid., pp. 65, 66. 



