102 'Journal of Comparative Neurology and Psychology. 



This work was begun under the direction of Dr. H. H. Don- 

 aldson, to whom the writer is indebted for many suggestions. 



THE SPINAL GANGLION. 



/. The distinction between the large and the small cells and the 

 junctional significance of the two forms. — It has long been known 

 that there exist in the spinal ganglion two well marked types of 

 cells, which differ from each other both in size and staining reaction. 

 As early as 1886 v. Lenhossek made a careful study of the small 

 cells and expressed an opinion concerning their functional sig- 





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'. ■at' 



r ^'"^^Bm 



%^.^s^- ^l-' ^X >■ 







'■••^tFlitl -^ 



Fig. I. The drawing represents a section 5,u thick from a spinal ganglion of a white rat, 

 prepared by a modification of Donaggio's Method VII, Zeiss, ocular 4, Objective y'o. 



nificance. According to his description, which relates in this 

 instance to the spinal ganghon of the frog, these cells are very 

 small, sometimes not more than 5// in diameter; they are often 

 angular and possess a relatively small amount of cytoplasm sur- 

 rounding a large nucleus. In 1895 ^^ ^^^^ ^^ ^^^ previous descrip- 

 tion that the small cells are characterized not only by their size 



