XIV. An Account of an Appendix to the small Intestines of Birds . 
By James Macartney, Esq . F. R. S. 
Read March 21, 1811. 
Every author who has written upon the incubation of the 
egg , except Leveille', has admitted the existence of a direct 
communication between the yolk bag and the small intestine 
of the chick, to which the name has been sometimes given of 
Ductus Vitello-intestinalis. It was likewise known to Stenon, 
Needham, and Maitre Jan, that this duct remains in the 
form of a small coecum during life ; but I do not find that any 
anatomist was acquainted with the great size that this part 
possesses in particular species, or its internal structure and 
uses in the adult bird. 
I was led to examine this process more attentively than it 
had been by others, in consequence of meeting with it in the 
snipe, in which bird it surpasses in length the coeca of the 
great intestines. 
The appendix has an uniform structure in all the birds I 
have inspected for it. There appear to be but two tunics ; the 
external is the continuation of the peritonaeum ; the internal 
of the villous coat of the intestine. The inner surface of the 
intestines exhibits different appearances, according to the spe- 
cies. In some it furnishes fine villous processes, in others 
zig-zag or waving laminae, which produce a texture to the 
naked eye, like that of twilled cloth ; but whatever may be 
mdcccxi. L 1 
