Venniforon Appendix. 343 



in Kelly's great work on the appendix is very inaccurate. 

 Mitchell's work on the digestive tract is riddled with error, 

 especially his remarks on the wombat. Mitchell denies that 

 the wombat has a true vermiform appendix. He says the 

 wombat has two avian caeca, one of which has been mistaken 

 for the vermiform appendix. After making this amazing state- 

 ment, Mitchell says he has never seen a wombat caecum, but he 

 has seen a drawing of a wombat's caecum by Flower. 



The vermifornx appendix is a peculiar caecal shape which 

 occurs only in mammals. (Fig. 2.) To extend the study of the 

 appendix into birds is therefore futile. Mitchell has carried the 

 avian double caecum into mammalian work in the wombat to his 

 own confusion. After extended observations on the caeca of 

 many varieties of birds, we see nothing in them throwing any 

 light on the mammalian appendix. Caecal size varies greatly in 

 different varieties of birds ; for instance, the common laughing- 

 jackass (Daceln) of Australia has complete caecal atrophy, the 

 wedge-tailed eagle (Aqiiila audar) and the lyre bird (Menura 

 victoriae) each have two atrophic caeca about the size of a rice 

 grain, the cassowary (Casuarius) has two caeca about two and 

 a-half inches long. Pheasants, ducks, geese and swans have 

 well-developed caeca. It is interesting to note that the Nankeen 

 night-heron (X ycticorax ) has a single caecum like a mammal, 

 and that the Indian python has a well-developed single caecum. 

 The monitor (Varatrus) is particularly interesting because he 

 shows a caecum in the process of fornuition. These variations 

 of caecal development do not, however, lend themselves so 

 readily to explanation as the caecal variations that occur in 

 mammals, because we know less of the habits of these animals 

 than we know of the habits of mammals. 



Since Huxley defeated Owen several facts relative to the 

 appendix, familiar to Owen and described by him, have by later 

 Avriters been displaced, but by fallacies. (Fig. 3.) 



The rabbit in place of the wombat now is regarded by Mit- 

 chell as the possessor of a vermiform appendix. What does the 

 word vermiform mean? Worm-like. (Figs. 1, "2, 7.) 



Kecent work on the appendix has ignored shape and devoted 

 itself unsuccessfully to histological investigation ; a result which 

 nuist always follow when naked-eye anatomy is sui)|)lanted by 



