Chap. I. CALCIFEROUS GLANDS. 53 



the pharynx were not acid, those of the 

 gizzard doubtfully so, while those of the in- 

 testine were distinctly acid at a distance of 

 5 cm. below the gizzard. Even with the 

 higher herbivorous and omnivorous animals, 

 the contents of the large intestine are acid. 

 " This, however, is not caused by any acid 

 " secretion from the mucous membrane ; the 

 " reaction of the intestinal walls in the larger 

 " as in the small intestine is alkaline. It 

 " must therefore arise from acid fermenta- 

 " tions going on in the contents them- 



" selves In Oarnivora the contents 



" of the coecum are said to be alkaline, 

 " and naturally the " amount of fermentation 

 "will depend largely on the nature of the 

 "food."* 



With worms not only the contents of the 

 intestines, but their ejected matter or the 

 castings, are generally acid. Thirty castings 

 from different places were tested, and with 

 three or four exceptions were found to be 

 acid ; and the exceptions may have been due 



* M. Foster, 'A Text-Book of Physiology, 5 2nd edit. 1878, 

 p. 243. 



