Chap. I. EUDIMENTS. 27 



lised men habitually feeding on soft, cooked food, and 

 thus using their jaws less. I am informed by Mr. Brace 

 that it is becoming quite a common practice in the United 

 States to remove some of the molar teeth of children, 

 as the jaw does not grow large enough for the perfect 

 development of the normal number. 



With respect to the alimentary canal I have met 

 with an account of only a single rudiment, namely the 

 vermiform appendage of the caBcum. The ca3cum is 

 a branch or diverticulum of the intestine, ending in a 

 cul-de-sac, and it is extremely long in many of the 

 lower vegetable-feeding mammals. In the marsupial 

 koala it is actually more than thrice as long as the 

 whole body. 34 It is sometimes produced into a long 

 gradually-tapering point, and is sometimes constricted 

 in parts. It appears as if, in consequence of changed 

 diet or habits, the caecum had become much shortened 

 in various animals, the vermiform appendage being left 

 as a rudiment of the shortened part. That this ap- 

 pendage is a rudiment, we may infer from its small 

 size, and from the evidence which Prof. Canestrini 35 has 

 collected of its variability in man. It is occasionally 

 quite absent, or again is largely developed. The passage 

 is sometimes completely closed for half or two-thirds of 

 its length, with the terminal part consisting of a flat- 

 tened solid expansion. In the orang this appendage is 

 long and convoluted : in man it arises from the end of 

 the short caecuni, and is commonly from four to five 

 inches in length, being only about the third of an inch 

 in diameter. Not only is it useless, but it is some- 

 times the cause of death, of which fact I have lately 

 heard two instances : this is due to small hard bodies, 



34 Owen, ' Anatomy of Vertebrates,' vol. iii. pp. 416, 434, 441. 



35 ' Annuario della Soc. d. Nat.' Modena, 1867, p. 94. 



