56 SHINKISHI HATAI 
If we compare now the entire brain of the snapper with the 
stem of the albino rat brain (table 7) we notice a surprisingly 
close similarity. This we should expect since as was already 
stated the fish brain is practically represented by the stem, since 
the cerebral and cerebellar portions are relatively insignificant. 
Thus we notice the practical identity in the percentage values 
of the total nitrogen, lipoid nitrogen, and the amount of the 
lipoids. The percentage of water in the stem of the rat is how- 
ever far less than in the entire brain of the fish which may be 
accounted for by the fact that in the brain of the fish the cere- 
brum and the cerebellum, though small in, relative quantity; 
nevertheless are composed of structures rich in water, and thus 
bring the value of the water higher in the fish than in the stem 
alone of the albino rat brain. 
The nitrogen content of the lipoid is slightly higher in the fish 
brain than in the albino rat brain, though almost identical with 
that in the stem. This difference may be due to the quantita- 
tive difference in the proportion of various lipoids in which the 
nitrogen content is not the same. 
I now wish to consider the partition of the non-protein nitro- 
gen in the fish brain compared with the brain of the albino rat. As 
will be seen from table 7 the content of the non-protein nitrogen is 
considerably greater in the fish than in the rat brain. We also 
notice that the greater part of the non-protein nitrogen is repre- 
sented by the nitrogen of the amino acids. The nitrogen values 
given by both the urea and ammonia are small and are practi- 
cally identical both in the fish and rat. The greater amount of 
non-protein nitrogen found in the fish brain in comparison to the 
rat is interesting, though I am unable to explain this difference 
satisfactorily. I wish however to call attention to two factors 
which may have some bearing on the difference just noted. 
1. It seems probable that on account of the low grade of or- 
ganization of the fish brain the physical consistence of the nervous 
system may not be as stable as that of the more highly organized 
mammalian nervous system, and thus the wear and tear process 
may be greater and produce a correspondingly greater amount 
of waste products in the fish brain. | 
