NON-PROTEIN NITROGEN, BRAIN OF FIGHTING RATS 81 



A series of researches which have been carried on by Dolley 

 ('09, '09 a, '10, '11) show clearly that not only as the result of 

 extreme physical exercises, but even during normal activity, or as 

 the result of surgical shock, the Purkinje cells of the cerebellum 

 show pronounced alterations, not only in structure of the cell 

 body, but in the nucleus-plasma relation. The investigation of 

 Mann ('95) shows clearly the effect of anesthetics on the Nissl 

 granules of nerve cells in producing the so-called chromatolysis, 

 which takes many hours for complete recovery. All these in- 

 vestigations demonstrate that the nerve cells are readily influenced 

 by shock, fatigue, chemical reagents, etc. These cytological 

 alterations of the nerve cells under varied conditions indicate a 

 considerable metabolic activity of the nervous organ, and the 

 increase of non-protein nitrogen in the brain during the great 

 emotional disturbance, which is noted in the present investiga- 

 tion, may thus be regarded as partly the result of activity of the 

 nervous tissue itself. It is the hope of the present writer to 

 further investigate this problem and at least to analyze the non- 

 protein nitrogen bodies here determined into their components 

 (urea, ammonia, amino acids, etc.) in order to throw further light 

 on the source of these metabolites. 



CONCLUSIONS 



1. The rats which were stimulated electrically for the period 

 of ten to twenty-four hours show a relatively greater amount of 

 non-protein nitrogen in the brain than do the control rats. 



2. Similar stimulation for six hours does not increase the nor- 

 mal content in the 'non-fighting' rat, but those rats which do 

 fight show an increase of the metabolites in the brain. 



3. The rats which fought violently produced a considerably 

 increased amount of non-protein nitrogen, even after one to four 

 hours of stimulation. 



4. The rats which fought severely for one hour show return to 

 the normal content of the non-protein nitrogen in the brain 

 after forty-two hours of rest. 



5. The increase of non-protein nitrogen in the brain, as the 

 result of severe fighting, is interpreted as partly due to metab- 



THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 31, NO. 2 



