Fatigue of Excitation and Fatigue of Depression etc. 51 



the kat abolie, the katabiotic. Out of the former comes its potential 

 irritability-; through the latter the kinetic manifestation of irritability 

 and the subsequent conduction of the liberated energy which is 

 secondary. This is its specialized work, its function, as conceived 

 from anatomical interpretation. It has come to the differentiation 

 peculiar to any organism to accomplish just that in best fashion. 

 With apology for the truism, so far as relates to its sole part in the 

 scheme of life, the nerve cell exists only to function. Its function is 

 primordial and so also the anatomical phenomena associated with 

 function are primordial. When one accepts the profound changes in 

 size and shape, the fixed and constant upset of the nucleus-plasma 

 relation and the gradual disappearance of chromatin as phenomena of 

 activity itself, there is no less a physical basis for fatigue of excitation 

 than for fatigue of depression. The only other factor from the 

 functional point of view is the by-products of this function. These 

 are purely secondary in their relation. While it is possible to conceive 

 that under certain abnormal conditions the reactive effect of the by- 

 products may become of first moment, it is impossible under normal 

 conditions. For part of the evolutionary development of the organism 

 has been directed to their ready and efficient removal. A circulating 

 medium receives them, the lungs and kidneys dispose of them. No 

 one doubts that they play a rôle but it is a minor one. 



There is abundant evidence on the physiological side from the 

 experiments here recorded to support the anatomical proof that these 

 waste products are of secondary importance in the work of the cell. 

 In the first place their effect in general was transitory and even after 

 the largest doses the animal appeared quite normal after the lapse 

 of some hours. Mosso's (1890) results are not at all contradicted but 

 they are defined. To be compared with the transient effect on the 

 transfused dogs is the actual inability of a dog doing just as much 

 work but doing it himself in the treadmill to resume that work, not 

 on the next day but on the second day (Experiment M.-E. 8 3 L911a). 

 To ascribe that to muscular disability alone in the lighl of the 

 changed nerve cell morphology would be narrow« 



In the second place, the findings give a strong impression that 



