256 Journal of Comparative Neurology. 



on muscular tissue by Professor Loeb (59), Such facts show that a 

 theory of movements of the protoplasm of the neurones can not be 

 carried out without constantly interpreting the histological evidence in 

 terms of the histological procedure. 



The assumption underlying the theory of amoeboid movements, 

 so far, at least, as the Golgi method is used, is that the substance of the 

 cell in the living state extends as far as and no farther than the silver 

 deposit which is continuous with the particular cell. The real question 

 is as to just what the Golgi picture represents. No one supposes that 

 the injection of the air-tubes and blood-vessels in insects by the silver- 

 chromate stain represents exactly the nature of those tissues. Why 

 should we assume that the nerve branches figured in the same sort of 

 preparations actually occupy, down to the finest ramifications, all the 

 places where you get the chrome-silver precipitate ? In saying this, 

 there is no desire to depreciate the value of the discovery of this meth- 

 od. Certainly we can see details here that no other method ever re- 

 vealed. The question is as to the warrant in the use of any method 

 for basing a physiological theory solely, or chiefly, upon small differ- 

 ences which may be due to the effect of the reagent alone. 



The fact that fatigued or pathological cells show a different reac- 

 tion from normal cells is not surprising. Naturally they would offer 

 less resistance, to speak of nothing else, to the impregnating solution. 

 This view is supported, moreover, by researches such as those of Heger 

 (44) which show that contraction, varicosity, and the disappearance of 

 the gemmules do not invariably coexist even in the case of stimulated 

 or narcotized cells. Any one of these changes may exist independently 

 of the others. 



It is not the purpose of this article to attack the results of these 

 investigators, but to show that there is this important point which can- 

 not be overlooked, that the effects of the reagent have not been care- 

 fully discriminated from effects due to variations in the reaction of the 

 cell according to its particular physiological condition. It is not denied 

 that the neurones may possess an amoeboid property. It is simply de- 

 nied that the evidence which has been confidently put forward in sup- 

 port of the theory, is wholly trustworthy as it has been employed. The 

 real problem still remains, which is to demonstrate the existence of this 

 property in the living tissue. It must be shown in some way which will 

 obviate the effects of the reagents used, that there is an actual change 

 in the spatial relations of the ultimate ramifications of the nerve cells. 



Since the completion of this article there has appeared the abstract 

 of a paper by R. Weil and R. Frank from the Pathological Institute of 



