Historical. 



The great amount of work devoted to the mor- 

 pliology of the nerve cell is in the main aside from the 

 problem in hand. It need be here referred to simply 

 as it furnishes the structural mechanism necessary for 

 a conception of the physiological working of the gang- 

 lion cell. This is furnished by Schultze/ to whom is 

 justly ascribed the credit of demonstrating the fibrillar 

 and granular structure of nerve cells. Later methods 

 have, however, demonstrated this more sharply ; and 

 for the best of these we are chiefly indebted to Pro- 

 fessor Kupffer* and Boveri.^ This method consists, 

 essentially, of hardening a perfectly fresh nerve in os- 

 mic acid and subsequently staining with acid fuchsin. 

 Seen in section after this treatment, the medullary 

 sheath appears black, and, what is of most interest 

 here, the axis cylinder shows fine red fibrils in a finely 

 granular matrix. The ganglion cell by this method is 

 found to consist, beside nucleus and nucleolus, of a 

 dense tangle of fibrils, unquestionably the same as 

 those occurring in the axis cylinder, with an irregu- 

 larly granular material filling the spaces between the 

 fibrils. We are thus given at least the two things 

 necessary for a nerve mechanism : the fibril to con- 

 duct, and, in close connection with this, some sort of 

 substance, changes in which may serve to originate or 

 modify the nerve impulse. 



Of great significance to the problem in hand is such 

 work as Heidenhain and Langley have done on the 



' General characters of the structures composing the nervous 

 sj'stem. Max Schultze, Strieker's Manual of Histology, p. 116. 



'' Ueber den Axencylinder markhaltiger Nervenfasern. Prof. C. 

 Kupffer. (Sitzgb. d. math. phys. Klasse d. k. bavr. Akad. d. AVis- 

 sensch. 1883, H. 3.) 



'Beitrage zur Kenntniss der Nervenfasern. Theodor Boveri, 

 Munich, 1885. 



