THE TRUE CiECAL APEX, OR THE VERMIFOKM APPENDIX. 91 



throughout the total length of the caeca. When the caeca are 

 short they are merely masses of lymphoid tissue, but when long, 

 the lymphoid tissue tends to be diffused throughout the entire 

 length of the cseca. In all cases the lymphoid tissue is present 

 to a much greater extent in the cseca, than in any other part of 

 the intestinal canal. 



Mammalia. 



Turning next to the mammals, I was unfortunately unable to 

 obtain any specimens of the Monotremes, and of the Marsupials 

 only one, the red kangaroo. So far as could be ascertained, 

 there is no special aggregation of leucocytes in the csecum or in 

 any other part of the alimentary canal ; there is merely a reticu- 

 lated network, embedded in which are some coarsely granular 

 leucocytes, few in number and widely diffused. It must, how- 

 ever, be remembered that the Marsupials, as a group, comprise 

 many divergent types, and consequently some divergences are 

 only to be expected in the case of the minute anatomy of the 

 cffical apex. It is to be regretted that more specimens of this 

 strangely interesting order were not obtainable. 



Edentata. 



Of the Edentates, Hoffmann's sloth alone was examined. In 

 this animal there is no csecum, consequently the junction 

 of small and large intestine was submitted to microscopical 

 examination, but the mucosa displays no features of any im- 

 portance. 



Ungulata. 



Of the Ungulates, specimens of the csecal apices of the pig, 

 the sheep, and the Stanley chevrotain were examined. In all 

 three species the c£eca are long, and the lymphoid tissue is 

 diffused throughout the mucosa. 



The Ungulata, or at all events those examined, resemble the 

 domestic fowl rather than the pigeon, inasmuch as the cffica 

 are long, and the lymphoid tissue tends to be diffused through- 

 out its mucosa. They all resemble the types in the all-impor- 

 tant respect that that lymphoid tissue is more especially well 



