100 MATHILDE L. KOCH AND OSCAR RIDDLE 



ferentiated, or less old, than are these parts of the brain in nor- 

 mals of equivalent age. Further, the evidence obtained from 

 the older strongly ataxic brains is more decisive than that 

 obtained from the younger less ataxic brains. 



Distribution of sulphur and phosphorus in cerebrum and 

 cerebellum-medulla 



In table 6 are given the data on the distribution in cerebrum 

 and cerebellum-medulla of sulphur and phosphorus calculated 

 in per cent of solids. That method of calculation scarcely 

 changes 13 the description already given above in terms of total 

 sulphur and total phosphorus. Particular attention may be 

 directed only to differences in distribution of these elements in 

 the cerebrum and cerebellum-medulla. These data are the 

 first thus far obtained for any bird. 



Protein-sulphur is more abundant in the cerebrum than in the 

 cerebellum-medulla. Lipoid-sulphur and extractive-sulphur is 

 distinctly less in the cerebrum. The older birds (598 and 600 

 days) have markedly less sulphur in all fractions of the cerebrum 

 than have the younger birds (205 and 206 days). In the cere- 

 bellum-medulla there is less of difference due to age. This prob- 

 ably indicates that the maximum sulphur content of the pigeon 

 cerebrum is reached at nearly 206 days and thereafter decreases 

 in relative amount (table 7). The sulphur of the cerebellum- 

 medulla suffers no marked decrease during this period (206 to 

 600 days). Most of the sulphur of cerebrum and cerebellum- 

 medulla is protein-sulphur. 



The phosphorus of both the cerebrum and the cerebellum- 

 medulla is chiefly lipoid-phosphorus. Protein-phosphorus and 

 extractive-phosphorus are present in almost equal quantity in 

 both parts of the brain. All three fractions of phosphorus are 



13 Only two of the figures compared above show a different relation to each 

 other under the two methods of calculation. These occur in the lipoid-phos- 

 phorus and extractive-phosphorus of the cerebellum-medulla of the older ataxic 

 group. Both became higher in the ataxic than in the normal. The numerical 

 result is the same as before: six figures still indicate the relative immaturity of 

 the organ and three figures are opposed. 



