1^8 PROCEEDINGS OF THE ACADEMY OF [Jan., 



OBSERVATIONS ON TUPAIA, WITH REFLECTIONS ON THE ORIGIN OF 



PRIMATES. 



BY HENRY C. CHAPMAN, M.D. 



According to many anatomists, "the Twpaice possess a large 

 coeciim."^ It appears Avorthy of mention, therefore, that on opening 

 recently the abdominal cavity of a specimen of Tupaia ferruginca 

 from Borneo not a trace of a coecum was to be seen (PI. IX, fig. 1), 

 confirming the statement recently made by the writer^ that the coecum 

 was not invariably present in that Insectivore, nor was it present 

 in a recently examined specimen of T. pictum. It may be stated, 

 in a general way at least, that in mammals in Avhicli the stomach is 

 large the coecum is small, and vice versa. This inverse relation of 

 the stomach and coecum as regards size appears to be conditioned by 

 the fact that in cases where gastric action is limited by the small size 

 of the stomach, the lack of digestion is made up by the digestive action 

 that goes on in the coecum. It is not to be supposed, howeA'er, that 

 the coeciun secretes a digestive juice like that of the stomach, but 

 rather that the proteid elements of the food and the acids developed 

 from the latter by fermentation act upon the residue of the food in 

 the coecum like the pepsin and hydrochloric acids of the gastric juice. 



In cases, therefore, in which the stomach is large, as in that of the 

 Tupaia examined, it might be expected that the coecum would l^e found 

 to be small, or even altogether absent". As a matter of fact, in the 

 specimen of Tupaia dissected the stomach was relatively large, meas- 

 uring in its long diameter 5 cent. (2 inches), the animal itself, from the 

 vertex to the root of the tail, measuring only 20 cent. (S inches). 



The stomach was found disteraded to its utmost capacity, presenting 

 an almost globular form, and filled with what ay)peared to be princi- 

 pally the remains of vegetal^lc food, though some remains of insects 

 were present. As gastric digestion appeared to be largely accom- 

 plished by the stomach in the case (",f the Tupaia examined, the 

 entire absence of a ca'cum becomes, after what has just been said, 

 intelligible. The intestine, measuring 71.2 cent. (28.5 inches), ex- 

 hibited throughout a luiiform diameter, and was loosely suspended 

 from the duodenum to the rectum by a continuous fold of peritoneum. 



1 Huxley, Anat. of Vertebrated Animals, 1872, p. 383; Carus, Zoologie, 1868- 

 75, S. 89. 



^ Proc. Acad. Nat. Sci. Phlla., 1902, p. 249. 



