FATIGUE IN NERVES. 159 



alternately, usually in minute periods by means of a commutator. The 

 movement at first is prolonged and practically equal in both sides. After 

 about an hour's stimulation the responses, after the minute's rest, in each 

 side is usually very small. The nerves received this half-hour's stimula- 

 tion 2 or 3 times a day. Owing to the great amount of muscular fatigue 

 involved in these experiments the blood supply must be a potent factor 

 in the recovery of the muscles. Since the constrictor influence was 

 removed from the cut side the circulation in the web was usually better 

 in that side. Consequently during the second and few succeeding 

 periods of stimulation the muscular responses were usually stronger 

 although not usually longer on the cut side than on the side with uncut 

 nerve. After a time the responses on the uncut side began to last much 

 longer than those on the cut side, and after 3 or 4 days this difference 

 was still more marked. The frogs usually died on the 5th or 6th day so 

 that no experiment was completed and absolute inactivity of the cut 

 nerve was not obtained. On the other hand if a nerve be simply cut 

 and then left for 5 or 6 days it yields equally powerful contractions as 

 the uncut nerve. Bethe 1 has also shown that stimulation causes loss of 

 sensitiveness in such cut nerves when compared with the opposite cut 

 but unstimulated nerve. 



5. Effect on the cells of the spinal ganglion of stimulating its 

 peripheral fibres with cut and uncut dorsal roots. 



On the hypothesis given at the beginning of this paper it might be 

 expected that a change would take place in the spinal ganglion cells on 

 peripheral stimulation of its afferent fibres only if the root fibres were 

 exciting the cells of the spinal cord. This fact has already been observed. 

 The cells of the spinal ganglion were one of the first objects in which 

 Hodge 2 found changes as a result of activity. Changes in these cells 

 as a result of activity have subsequently been found by Levi 3 , Pugnat 4 , 

 and Holmgren 8 . Steinach 6 , however, could find no changes in these 

 cells on stimulation of the nerve peripheral to the ganglion. Pick, who 

 had already 7 made a series of experiments and found changes due to 



1 Loc. cit. 



2 Journal of Morphology, vii. p. 95. 1892. 



3 Riv. di. pat. nerv. e ment. i. p. 169. 1896. 



4 Bibliogr. Anat. vi. p. 27. 1898. 

 6 Anat. Hefte. xv. p. 7. 1900. 



6 Pftuger's Archiv, Lxxvnr. p. 291. 1899. 



7 Deutsch. med. Wochensch. xxiv. p. 341. 1898. 



