86 DE RICHAED J. A. BERRY. 



its lymphoid tissue ; that there is no similar predominating 

 collection of lymphoid tissue in the large intestine ; that the 

 lymphoid tissue reaches its maximum limit in the appendix 

 within one week after birth ; and lastly, that there is nothing 

 to prevent the leucocytes contained in this lymphoid tissue of 

 the appendix from being extruded into the cavity of the gut. 



Carnivora, — Felis doinesticus, the Cat. 



Numerous specimens of the ctecum of the cat have been 

 examined from embryos, kittens at birth, kittens of two, four, 

 and seven days old, kittens a few weeks after birth, adult cats, 

 cats in whom the caecum was ligatured before removal, and 

 others in whom the duodenum and jejunum had been similarly 

 ligatured before removal, for purposes of comparison. 



Plate VII. 3, a longitudinal section through the cffical apex of 

 an adult cat, represents the typical appearances presented by 

 this part of the intestinal canal. The submucosa is seen to 

 consist of large amounts of lymphoid tissue, collected into well- 

 marked germ centres. The mucosa presents the customary 

 features of large intestine. As in the ral)bit, the characteristic 

 feature of the cffical apex of the cat is the predominating amount 

 of lymphoid tissue, as is shown, by way of comparison, in 

 Plate VII. 4, which represents a transverse section through the 

 large intestine of an adult cat. 



Passing next to a study of the development of the lymphoid 

 tissue in the caecal apex of the cat, PI. VIII. 5 illustrates the ap- 

 pearances presented by a transverse section through the caecum 

 of a full-term foetal kitten. There are the usual four coats, but 

 the submucosa contains little lymphoid tissue ; in fact, it closely 

 resembles in almost every detail the appearances presented by 

 the appendix of a full-term fcetal rabbit (PI. VIII. 2). 



At two days old (see PI. VIII. 6) the lymphoid tissue in the 

 submucosa is increased in amount, and at four days old (see 

 PL VTII. 7) it exceeds in thickness all the other coats put 

 together. At seven days old the lymphoid tissue is the most 

 prominent feature of the caecum (see PI. VIII. 8), and is already 

 collected into germ centres, though perhaps not to such an ex- 

 tent as in the older animals. 



