222 PHYSIOLOGICAL CHEMISTKY. 



intestine under physiological conditions are kept within certain 

 limits cannot be answered positively, still it may be asserted 

 that the acid reaction of the upper parts of the intestine 

 and the absorption of water in the lower parts are important 

 factors. 



Excrements. It is evident that the residue which remains after 

 completed digestion and absorption in the intestine must be differ- 

 ent, both qualitatively and quantitatively, according to the variety 

 and quantity of the food. In man the quantity of excrement from 

 a mixed diet is 120-150 grms., with 30-37 grms. solids, per 24 

 hours, while the quantity from a vegetable diet, according to VOIT, 

 was 333 grms., with 75 grms. solids. With a strictly meat diet the 

 excrements are scanty, pitch-like, and colored nearly black by 

 haematin and iron sulphide. The scanty excrements in starvation 

 have a similar appearance. A large quantity of coarse bread yields 

 a great amount of light-colored excrement. If there is a large 

 proportion of fat, it takes a lighter, clayey appearance. The decom- 

 position products of the bile-pigments seem to play only a small 

 part in the normal color of the faeces. 



The constituents of the faeces are of different kinds. We find 

 in the excrements digestible or absorbable constituents of the food, 

 such as muscular fibres, connective tissues, lumps of casein, grains 

 of starch, and fat which have not had sufficient time to be com- 

 pletely digested or absorbed in the intestinal tract. In addition 

 the excrements contain indigestible bodies, such as remains of 

 plants, keratin substances, nuclein, and others; also form-elements 

 originating from the mucous coat and the glands ; constituents of 

 the different secretions, such as mucin, cholalic acid, dyslysin, and 

 cholesterin; mineral bodies of the food and the secretions; and 

 lastly, products of putrefaction or of the digestion, such as skatol, 

 indol, volatile fatty acids, lime, and magnesia soaps. Occasionally, 

 also, parasites of different kinds occur ; and lastly, the excrements 

 contain micro-organisms, fungi of different kinds, sometimes in 

 such large quantities that the chief mass of the excrements seems 

 to consist of micro-organisms (v. JAKSCH). 



The reaction of the excrements is very changeable. It is often 

 #cid in the inner part, while the outer layers in contact with the 

 mucous coat have an alkaline reaction. In nursing infants it is 



