458 C. G. MACARTHUR AND E. A. DOISY 



The cerebrosides and sulphatids are present in slightly larger 

 amounts in the stem (table 5) than in the forebrain (table 2), 

 but in very much larger quantities than in the cerebellum (table 

 8). This would indicate that one of the main differences in 

 chemical constitution between the cerebellum and the rest of the 

 brain is in the amount of meduUation. 



Cholesterol, etc., is found most largely in the stem and least in 

 the cerebellum. 



The total lipins are not only largest in amount in the stem 

 (table 5) and least in the cerebellum (table 8), but possibly are 

 formed slightly earlier and at a more rapid rate in the same 

 order. 



In all divisions the proteins show in general variations exactly 

 opposite to that of the lipins. Thus with age there is a decrease 

 in percentage of solids (tables 2, 5, and 8). The total proteins 

 exist in but slightly different percentages in the different parts of 

 the fresh tissue (tables 1, 4, and 7), and they seem to be formed 

 at approximately the same rate in all. 



In an attempt further to analyze the meaning of these vari- 

 ations in protein content, the data frpm protein sulphur and 

 protein phosphorus are of value. It is probable that the greater 

 amount of protein -sulphur is in neurokeratin, a constituent of 

 supporting tissue, while the protein phosphorus is very largely 

 present as nucleoprotein b (0.6 per cent P), only a relatively 

 small amount being present as nucleoprotein a (0.11 percent P). 

 (The percentage amount of the former, 10 per cent, is about twice 

 that of the latter, 5 per cent in adult tissue.) From tables 1, 

 4, skid 7, then, it will be noticed that there is more than twice 

 as much nucleoprotein in the cerebellum as in other parts of the 

 brain. This difference prevails throughout growth. The stem 

 and forebrain differ but little in this respect. On the other hand, 

 protein sulphur (neurokeratin) is a little greater in the brain stem 

 than in the forebrain or cerebellum. To judge from these data, 

 one might state that the number of nuclei, or at least the amount 

 of nuclear material, is considerably larger in the cerebellum, while 

 the amount of supporting tissue is not very different in the 



