W. Koch and M. L. Koch 



Distribution of sulphur. 



Chemistry. PROTEIN S. This group represents sulphur in various amino- 

 acid combinations such as cystine or cysteine. The proteins in which this 

 sulphur fraction is found have been coagulated and rendered insoluble in 

 water by treatment with hot alcohol. 



LIPOID S. Ethereal sulphuric acid combinations are discussed under 

 sulphatides. 



NEUTRAL S. This group of compounds represents the total non-col- 

 loidal, water-soluble combinations of sulphur, minus the inorganic sul- 

 phates. As far as studied, they resemble in all their reactions a similar 

 group found in the urine and called by Bondzynski proteinic acids. They 

 represent, probably, larger cleavage products of the protein molecule or 

 complex non-coagulable, water-soluble polypeptides somewhat altered 

 by processes of oxidation. The sulphur of this fraction is represented 

 essentially by compounds included among the organic extractives, and 

 the sulphur is most often in an oxidized form like taurine or ethereal 

 sulphate. 



INORGANIC S (inorganic sulphates). Derivatives of sulphur directly 

 precipitated by barium chloride in hydrochloric acid solution. 



Anatomical distribution and physiological significance. The LIPOID S, 

 as has already been mentioned under the sulphatides, represents an essen- 

 tial constituent of the medullary sheath. The proportion in which it 

 occurs in the sheath can be considered as a measure of the maturity of 

 the sheathing substance. 



THE PROTEIN S AND NEUTRAL S will be considered together as they bear 

 an important relation to one another and as the combinations in which 

 they occur are essential constituents of all living cells. As has already 

 been stated, the study of these two groups of sulphur compounds gives 

 us a means of investigating the protein metabolism of the central nervous 

 system during its growth period. 



TABLE I. 



A comparison of neutral sulphur with protein sulphur in the brain of the albino 

 rat at different ages (figures in per cent of total sulphur}. 



During the early stages when growth is proceeding rapidly and chem- 

 ical activities may be considered to be at their height, the proportion of 



