40 THE DECENT OF MAN 



diverticulum of the intestine, ending in. a cul-de-sac, and is 

 extremely long in many of the lower vegetable-feeding mam- 

 mals. In the marsupial koala it is actually more than thrice 

 as long as the whole body." It is sometimes produced 

 into a long, gradually tapering point, and is sometimes con- 

 stricted 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 appendage is 

 a rudiment, we may infer from its small size, and from the 

 evidence which Prof. Oanestrini" has collected of its vari- 

 ability 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 flattened solid expansion. In the orang 

 this appendage is long and convoluted; in man it arises 

 from the end of the short csecum, 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, such as 

 seeds, entering the passage and causing inflammation." 



In some of the lower Quadrumana, in the Lemuridse and 

 Carnivora, as well as in many marsupials, there is a passage 

 near the lower end of the humerus, called the supra-condy- 

 loid foramen, through which the great nerve of the forelimb 

 and often the great artery pass. Now in the humerus of 

 man there is generally a trace of this passage, which is some- 

 times fairly well developed, being formed by a depending 

 hook-like process of bone, completed by a band of ligament. 

 Dr. Struthers," who has closely attended to the subject, has 



46 Owen, "Anatomy of Vertebrates," vol. iii. pp. 416, 434, 441. 



« "Annuario della Soc. d. Nat," Modena, 1861, p. 94. 



*^ M. 0. Martins ("De rUnite Organique," in "Revue dea Deux Mondes," 

 June 15, 1862, p. 16), and Haekel ("Generelle Morphologie," B. ii. s. 218), have 

 both remarked on the singular fact of this rudiment sometimes causing death. 



^ With respect to inheritance, see Dr. Struthers in the "Lancet," Feb. 15, 

 1873, and another important paper, ibid., Jan. 24, 1863, p. 88. Dr. Knox, 

 as I am informed, was the first anatomist who drew attention to this peculiar 



