ItUDTMENTS. 23 



tnals. 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 short- 

 ened in various animals, the vermiform appendage being 

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



Eendage is a rudiment, we may infer from its small size, and 

 :om the evidence which Prof. Canestrini f 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. 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. J 



In some of the lower Quadrumana, in the Lemuridae and 

 Carnivora, -as well as in many marsupials, there is a pas- 

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

 condyloid foramen, through which the great nerve of the 

 fore limb and often the great artery pass. Now 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, who has closely attended to 

 the subject, has now shown that this peculiarity is some- 

 times inherited, as it has occurred in a father, and in 110 less 



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



f " Annuario della Soc. d. Nat.," Modena, 1867, p. 94. 



JM. C. Martins ("De 1'Unite Organique," in "Revue d6s Deux 

 Mondes," June 15, 1862, p. 16), and Hackel ("Generslle Morpholo- 

 gic," B. ii, s. 278), have both remarked on the singular fact of this 

 rudiment sometimes causing death. 



With respect to inheritance, see Dr. Struthers in tke "Lancet," 

 Feb. 15, 1873, and another important 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 " 0? rea-t Artists 

 and Anatomists," p. 63. See also an important memoir on thfo pro- 

 cess by Dr. Gruber, in the " Bulletin de 1'Acad, Imp, de gfc, Peters- 

 bourg," torn, xii, 1867, p. 448- 



