7^34 THE HARVEIAN ORATION. 



demonstration of the capillary circulation, unknown to the discoverer 

 of the makroscopic circulation. The experiment to which I refer 

 has its results fairly represented in the accompanying drawing 

 (Fig. i) of a specimen prepared by myself at a class-demonstration. 



Fig. I, — Vermiform Appendix, Caecum, and parts of Small Intestine and 

 Colon of Rabbit {Lepus cuniculus), with the Peyerian and also some of the 

 mesenteric glands in conne^^ion with them injected. The ileum and colon 

 lie side by side, the former describing a siphon-shaped curve before ending 

 in a dilatation, known as the * sacculus rotundus ' and homologous with the 

 aggregation of Peyerian follicles situated in man just anteriorly to the ileo- 

 caecal valve. The sacculus rotundus occupies the centre of the figure ; above 

 and a little to the left of it another somewhat similar aggregation of Peyerian 

 follicles is seen just beyond the ileocolic valve. The colon curves backwards 

 externally to and concentrically with the ileum. The caecum consists of two 

 portions : one larger in calibre, thinner in walls, and sacculated spirally; the 

 other, the homologue of the human 'appendix vermiformis,' smaller in 

 calibre, but with much thicker walls. It has been injected as described in 

 the text, and the injection is seen to have passed into some mesenteric glands 

 situated close to the junction of the two segments of the caecum, and between 

 it and the colon. 



