112 



HODGE. [Vol. VII. 



to Vulpian's (82) experiments upon guinea pigs, in which he 

 was unable to discover any changes in the spinal cord. 



Upon the purely physiological histology of nerve tissue little 

 work has been done. 



For the nerve fibre, Kiihne notes a change in the axis cylinder, 

 a disarrangement and shrinking together of the fibrilae with the 

 appearance of vacuoles between them, in the nerves of the nic- 

 titating membrane of the frog due to only ten minutes' unipolar 

 stimulation of the nerve root within the skull (30, p. 56 ; Taf. 

 D, Fig. 64). But physiological evidence has been piled up by 

 Bernstein and Widenskii, and later by Bowditch (8 and 9) 

 and Szana (79), all to the effect that a nerve fibre is not sus- 

 ceptible of fatigue. That an excised nerve dies more quickly 

 when stimulated than when left at rest, is conclusively proved 

 by Lee (40) ; and why this should occur, if no change associated 

 with activity takes place, is difficult to explain. 



For the nerve cell, possibly the observations of Svierczewski 

 (78), as long ago as 1869, have a physiological bearing. This 

 observer studied the cells of the frog's sympathetic ganglia 

 kept alive in aqueous humor or lymph, and subjecting them to 

 different conditions, observed the effects. From what more 

 recent work is bringing to light, it is significant to note that 

 active changes were discovered only within the nucleus. The 

 nucleoli were observed to wander about in the nucleus, some- 

 times in a most lively fashion, for as long as twenty-four hours. 

 On exposing the cells to carbon dioxide, a finely granular pre- 

 cipitate suddenly formed within the nucleus, which redissolved 

 on treatment with oxygen or hydrogen ("paraglobulin-reaction"). 

 This process was accompanied, under certain conditions, by a 

 marked shrinkage, the rounded form of the nucleus being altered 

 to an irregular or "zickzack" outline, the nucleolus at the same 

 time being lost to view. 



Somewhat similar observations were made by Freud (13) upon 

 the living ganglion cells of Astacus. He describes shreds and 

 angular-shaped particles which change form and position within 

 the nucleus. 



The only paper devoted to the exact problem in hand was 

 written in 1889 by Bohdan Korybut-Daszkiewicz (32). The 

 author states the exact question : " Is the activity of the cen- 

 tral nervous system accompanied by changes recognizable with 



