PROTEIDS OF NERVOUS TISSUES. 



117 



marised in the following table of mean analyses. The organs were from 

 adult human beings, dogs, cats, and monkeys : 



This table illustrates the fact that the amount of grey matter, of 

 water, and the percentage of proteid in the solids, vary directly the one 

 with the other. This is very well seen in the different regions of the 

 spinal cord. The percentage of proteid in the white matter of the 

 brain is a little higher than in the spinal cord; this exception is 

 perhaps to be explained by the high percentage of neurokeratin l in 

 white matter, which, according to the methods used, would be included 

 with the proteids. 



Reaction of nervous tissues. Heidenhain 2 and Gscheidlen 3 state that 

 the normal reaction of the axis cylinder is alkaline ; on death or on 

 long-continued activity the reaction becomes acid. They further state 

 that the grey matter is acid even during life. 0. Langendorff 4 found 

 the reaction of the central nervous system alkaline during life ; the 

 alkalinity rapidly diminishes after death, or on stoppage of the circula- 

 tion. S. Moleschott and Battistini 5 found both central and peripheral 

 portions of the nervous system acid, especially the grey matter ; this was 

 increased by activity. 



In my own work I found in animals that the fresh tissues were 

 invariably alkaline, but they became, rapidly acid, especially the grey 

 matter. In the human brains I received from the post-mortem room the 

 reaction of the grey matter was always, of the white matter often, acid. 

 This I put down to changes after death, for at least twenty-four hours 

 had always elapsed since death. 



The acidity is due to lactic acid ; but, according to Miiller and 

 Gscheidlen, it is not sarcolactic acid but the fermentation lactic acid 

 (optically inactive ethylidene -lactic acid). Miiller also obtained traces 

 of formic acid. 



Proteids of nervous tissues. The large quantity of these, especi- 



1 The percentage of neurokeratin is in grey matter, 0'3 : in white matter, 2 '2 to 2 '9 ; and 

 in nerve, 0'3 to 0'6 (Kiihne and Chittenden, Ztschr.f. BioL, Munchen, Bd. xxvi. S. 291). 



2 CentralU.f. d. med. Wissensch., Berlin, 1868, S. 833. 



3 Arch.f. d. ges. Physiol. Bonn, Bd. viii. S. 171. 



4 NeuroL CentralbL, Leipzig, 1885, No. 14; Centralbl. f. d. mcd. Wissensch., Berlin, 

 1886, No. 25. 



5 Arch. ital. de biol, Turin, vol. viii. p. 90 ; Chem. Centr.-BL, Leipzig, 1887, S. 1224. 



