THE PHYSIOLOGY OF THE NEURON. 521 



den 22 found that "all material treated according to the slow 

 method of Golgi shows, as a rule, an almost absolute freedom 

 from varicosities; varicose cells occasionally occur/' The 

 mixed method and the rapid were found to yield practically 

 the same results when the dendrites had taken the stain: the 

 gemmules were almost invariably present and regular. In 

 some sections almost every dendrite was varicose; in others 

 hardly any. All these results were similar whether normal or 

 "toxic" material was used, and the author concludes that "it 

 is impossible for an unprejudiced observer to differentiate or 

 distinguish between the two kinds of material." Lugaro, 23 

 who has upheld the retraction theory, also reached the con- 

 clusion that "imperfect fixation is very largely, though not 

 entirely, responsible for the formation of varicosities and the 

 disappearance of gemmules." Weil and Frank summarize what 

 a review of the literature of the subject shows, when they say: 

 "The findings have been in almost every case positive, although 

 there are occasionally records of negative results and even 

 contradictions, as, for example, between the investigations 

 of Demoor and of Soukhanoff on the effects of chloroform. 

 . . . Eetraction of the gemmulse and coincident swelling of 

 the dendrites form the essential features of every description." 



Judging from the foregoing estimates as to the effects 

 of stains upon dendrites, these phenomena are to be consid- 

 ered as artifacts: i.e., as artificially produced changes. Under 

 these conditions, it is clear that the latter should appear, irre- 

 spective of the condition of the animal at the time of its death: 

 i.e., whether under the influence of toxics as stated, fatigue, 

 etc. 



That prevailing views in this connection are erroneous is 

 our firm belief after a critical analysis of available experimental 

 evidence. Particularly instructive and valuable in this con- 

 nection are the experiments of H. H. Goddard, 24 which con- 

 sisted "in cutting through the entire head of the animal at a 

 single blow with a very thin sharp knife, the parts of the head 

 falling instantly into large dishes of Cox's solution warmed 



22 H. H. Bawden: Journal of Comparative Neurology, May, 1900. 



23 Lugaro: Rivista di patol. nerv. e ment., vol. iii, 1898. 

 14 H. H. Goddard: Jour, of Compar. Neurol., Nov., 1898. 



