406 



SHIGEYUKI KOMINE 



It must be stated that in the total nitrogen those nitrogen 

 values which belong to the non-protein substances, as well as 

 those belonging to the lipoids, are also included. Any disturb- 

 ance which may arise from such treatment should be very slight, 

 owing to the greater amount of protein nitrogen contrasted with 

 the nitrogen of the metabolic products. We find in chart 2 

 that in general the variation of non-protein nitrogen in relation 

 to the total nitrogen is essentially similar to the relation found 

 between entire brain substance and the non-protein nitrogen. 

 This is to be expected, since the ages of rats examined are close 

 to each other, and hence the water content, as well as the'amount 



0.5 

 0.4 



0.3 



0.2 



0.1 







-0.1 



-0.2 



-0.3 



-0.4 



-0.5 



10 



15 



20 



24 



Chart 2 Illustrating the relation between the total nitrogen in the brain and 

 metabolic products found during the twenty-four hours following feeding. 



of myelin substance present in each brain, should not differ so 

 much as they would, for instance, if the cerebrum was compared 

 with the spinal cord of the same animal. This result was pleas- 

 ing, since the close similarity found here, and that found in 

 connection with the relation of the entire brain to the metab- 

 olites, shows the trustworthiness of the present technique 

 which is suited to such experiments where very slight differences 

 between the control and test animals are present. 



We conclude from these additional facts that the non-protein 

 nitrogen in the brain shows a periodic alteration during the 

 twenty-four hours after feeding. 



