51 



Dr. Withrow Morse and the writer 89) studied the 

 changes in reaction in dying tissue, in connection with the 

 senior author's work on autolysis. The liver of guinea pigs was 

 taken out immediately after they had been killed, and ground 

 up in a mortar. Sometimes they were first frozen by means of an 

 ethyl-chloride spray, sometimes used without freezing. They were 

 taken up in a small quantity of destilled water and the whole 

 mass was then put in the cup of a Leeds and Northrup 

 potentiometer, type K. P H readings were made at different 

 intervals. It appeared that very soon after death occurred, a 

 relatively tremendous acidity was established, even up to PH : : 4, 

 but that afterwards this acidity gradually diminished to near 

 the neutral point. No trial could be made to study more in 

 detail the nature of this acid on account of our poor equipment ; 

 we supposed that we might have to do with lactic acid. 



Lactic acid is also formed in autolysates of the snail's liver. 

 Biedermann and M o r i t z 9) found that if the digestive fluid 

 of Helix was left alone, even with shreds of fibrin in it, no 

 decay could be observed. If decaying pieces of fibrin were put 

 into that liquid, the decay stopped in a very short time. A 

 strongly acid reaction which he found in these samples solved 

 the problem. Whereas e. g. in crabs the digestive fluid decays 

 at once here the acidity prevented all bacterial growth. He 

 show showed that lactic acid was the cause of this acidity. 



A digest of crushed liver substance also appeared to contain 

 a large quantity of this acid. It did not digest proteins, but 

 a coagulation of the material was observed caused by the acidity. 

 That lactic acid was also present here, could be shown by 

 means of Uffelmann's reagent, a 2 / phenol treated with 

 dilute ferric chloride till of an amethyst violet color. This reagent 

 is decolorised by mineral acids, but colored yellowish by lactic 

 acid and some other organic acids. The development of this 

 acid is due to bacteria according to Biedermann: chloroform 

 and thymol prevent its formation. 



Other experiments showing this same phenomenon came to 

 my attention in a paper of Lindemann 80). This author 

 finds in 100 gr. autolysed liver of a rabbit an acidity titrable 

 with 7.6 c.c. decinormal NaOH. Estimated as butyric acid this 

 would mean 66.9 mgr. 



As we see, this phenomenon occurs rather regularly in the 

 most divergent groups. In our digests of starfish ,,liver' 

 found, as mentioned above, an acid of some kind to be present. 

 This acid is soluble in ether - - this is in fact the case with lactic acid. 

 From a small quantity of material I extracted the acid by means 

 of ether; Uffelmann's reagent lost its violet color and changed 

 into yellow. These facts make it rather probable that here 

 have to do with lactic acid, though they do not prove it defini- 

 tively, since many other organic acids may give the same reaction. 



