LACTIC ACID. 95 



alcoholic solution, and the magnesian and zinc salts were crystal- 

 lometrically examined and quantitatively analysed, so that there 

 can be no doubt regarding the existence of lactic acid in this fluid. 



Tiedemann and Gmelin*, and Valentinf, attribute the acid 

 reaction of the mucus of the small intestines to lactic acid, because 

 this mucus, on incineration, yields an ash abounding in carbonates, 

 which, at all events, could not be the case to such a degree, if the 

 free acid of this mucus were a mineral acid. 



Moreover, the contents of the large intestine have often an acid 

 reaction, and indeed constantly after the use of vegetable food: 

 in two cases in which I was able to collect large quantities of these 

 contents from a preternatural anus in the ascending colon, I 

 obtained quite sufficient lactic acid to test crystallometrically the 

 zinc and magnesian salts. 



The fluid secreted by the large intestine (and indeed by the 

 lower portion of the ileum) has always an alkaline reaction ; hence 

 the outer parts of the contents of the large intestine are for the 

 most part neutral or alkaline; after the use of vegetable food 

 the inner portion is, however, always acid, as was ascertained by 

 Steinhauser.* 



Whether lactates constantly occur in the chyle must for the 

 present remain undecided. In the chyle obtained in two cases 

 from the thoracic duct of the horse (one horse having been fed with 

 oats two hours before he was killed, and the other with starch-balls), 

 lactic acid was recognised with certainty. 



Here, as well as in the investigation of the alcoholic extract of 

 lymph or blood, we must be careful in reference to the salts of the 

 fatty acids ; and, consequently, after the separation of the pure 

 lactic acid by ether, the extract should be boiled with water to 

 remove the non- volatile fatty acids, and the solution, when cooled, 

 should be filtered ; the lactic acid should then, in the manner we 

 have already described, be transferred to baryta, from this to oxide 

 of copper, and from the latter to oxide of zinc, so as to separate 

 as much as possible the volatile fatty acids. This investigation 

 leaves no doubt regarding the existence of lactates in the chyle of 

 horses during the digestion of amylaceous food. 



No one has yet definitely established the presence of lactic acid 

 in the lymph, although its presence in the fluid is by no means 



* Verdauung. Bd. 1, S. 349. 

 t Lehrb. d. Physiol. d. Menschen. Bd. 1, S. 343. 



% Experimenta nonnulla de sensibilitate et functionibus intestini crassi, Diss. inaug. 

 Lips. 1842. 



