Chap. I. 



Rudiments. 



21 



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. Canestrini 47 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 flattened solid expansion. In the orang this appendage is long 

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

 caecum, and is commonly from four to five inches in length, 

 being only about the third of an inch in diameter. Kot only is 

 it useless, but it is sometimes 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 inflam- 

 mation. 48 



In some of the lower Quadrumana, in the Leimrridse and 

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

 the lower end of the humerus, called the supra-condyloid fora- 

 men, through which the great nerve of the fore limb and often 

 the great artery pass. Kow in the humerus of man, there is 

 generally a trace of this passage, which is sometimes fairly well 

 developed, being formed by a depending hook -like process of 

 bone, completed by a band of ligament. Dr. Struthers, 49 who lias 

 closely attended to the subject, has now shewn that this 

 peculiarity is sometimes inherited, as it has occurred in a father, 

 and in no less than four out of his seven children. When pre- 

 sent, the great nerve invariably passes through.it; and this 

 clearly indicates that it is the homologue and rudiment of the 

 supra-condyloid foramen of the lower animals. Prof. Turner 

 estimates, as he informs me, that it occurs in about one per cent, 

 of recent skeletons. But if the occasional development of this 

 structure in man is, as seems probable, due to reversion, it is a 

 return to a very ancient state of things, because in the higher 

 Quadrumana it is absent. 



There is another foramen or perforation in the humerus, 



47 'Annuario della Soc. d. Nat.' 

 Modena, 1867, p. 94. 



48 M. C. Martins (" De l'Unite 

 Organique," in ' Revue des Deux 

 Mondes,' June 15, 1862, p. 16), and 

 Hackel (' Generelle Morphologie,' 

 B. ii. s. 278), have both remarked 

 on the singular fact of this rudi- 

 ment sometimes causing death. 



49 With respect to inheritance, 

 ese Dr. Struthers in the ' Lancet,' 



Feb. 15, 1873, and another im- 

 portant^ paper, ibid., Jan. 24, 1863, 

 p. 83. Dr. Knox, as I am informed, 

 was the first anatomist who drew 

 attention to this peculiar structure 

 in man ; see his ' Great Artists and 

 Anatomists,' p. 63. See also an im- 

 portant memoir on this process by 

 Dr. Gruber, in the * Bulletin de 

 l'Acad. Imp. de St. Petersbourg, 

 torn. xii. 1867, p. 448. 



