VESTIGIAL ORGANS 



it is now customary, as an incidental step in many abdominal 

 operations, to remove the appendix on the assumption that 

 a person is better off without it than with it. There is no 

 reason to suppose that the appendix in man performs any 

 function whatever, and since its removal is unattended by 

 any subsequent inconvenience, it is commonly set down as a 

 useless organ. 



In other mammals than man the vermiform appendix or 

 its equivalent presents 

 a variety of conditions. 

 It is not always easy in 

 these lower forms to 

 distinguish the exact 

 limits between caecum 

 and appendix, but in 

 the rabbit, for instance, 

 a large and highly 

 complex caecum com- 

 municates freely and 

 easily with an ex- 

 tended and apparently 

 highly functional ap- 

 pendix. Without 

 doubt these two parts 

 are of great value in 

 the digestive functions 

 of this mammal, and the same may be said of them in many 

 other animals. They are both greatly reduced, however, in 

 the monkeys and in the anthropoid apes, where they are rep- 

 resented by a condition almost exactly like that in human 

 beings. In consequence of the state of the vermiform 

 appendix as seen in man it may be set down in the human 

 species as a truly vestigial organ. 



[43] 



B 



Fig. 7. — A, Caecum and appendix of 

 a rabbit, showing the small intestine 

 entering from above and the large in- 

 testine emerging to the left; B, Similar 

 parts in man, with the vestigial vermi- 

 form appendix to the right. 



