XI.] 



THE ALIMENTARY SYSTEM. 



447 



The proportion as to length borne by the small intestine to 

 the large is generally in Mammals less than in man, in whom 

 it is as five to one ; but the large intestine may be very 

 short (not more than a tenth the length of the body), as in 

 most Birds ; it may be, on the contrary, actually the longer 

 portion of the intestine, as in the Ostrich. 



The presence of a csecum is not quite constant in man's 

 class, and this structure is never found in Fishes, though it is 

 often present in Reptiles, and generally in Birds. In Fishes, 



FIG. 378. VISCERA OF THE COMMON FOWL. 



ce, oesophagus ; cp, crop ; pr, proventriculus ; g; gizzard ; /, liver ; gb, gall-bladder ; 

 p, pancreas ; d, loop of the duodenum enclosing the pancreas: si, small intes- 

 tine ; //, large intestine ; e, caeca ; o, oviduct ; u, ureter. The cloaca is cut open 

 and some feathers are represented attached to its margin. 



indeed, there are often many cascal appendages to the 

 intestine, but these will be noticed below in describing the 

 Pancreas. 



In man's class the caecum often presents an inverse degree 

 of size and complexity compared with the stomach. It may 

 be enormous, as in the Indris, the Hare, the Galeopithecus, 

 the Koala, and the Horse. It may be very simple and short, 



