604 THE NERVE CELL. 



the 'prolonged cessation of function of the sensory cells, since, after the 

 irritation produced by the severance of the nerve and cicatrisation of 

 the wound had passed off, they would be receiving no nervous impulses, 

 and would then tend to obey the general law, that atrophy results from 

 loss of function. The motor cells, on the other hand, would still be 

 receiving reflex and possibly also voluntary impulses, and their activity 

 would thus be maintained until the cut nerve fibres were regenerated. 

 In the event of these failing to become regenerated — as in the case of 

 an amputated limb — the motor nerve cells also become atrophied. 1 



Various other conditions besides those above noticed may determine 

 chromatolysis in nerve cells, e.g., certain drugs, such as acetate of lead, 2 

 arsenic, 3 bromine, antipyrin, cocain, 4 strychnin ; 3 intoxicants such as alcohol 

 in large doses, 3,5 and malonic nitrite 6 (which can be antagonised by hypo- 

 sulphite of soda) ; poisoning by disease-toxins, e.g., the toxins of rabies 

 and tetanus 3 (which can be antagonised by the corresponding antitoxins); 7 

 acute local anaemia (as by compressing the aorta), 8 and a rise of body 

 temperature experimentally induced. 9 



Whether the nucleated cell body plays any part in the starting of 

 nerve impulses, or in their modification, or has any other function than 

 that of regulating the nutrition of the nerve cell and its processes, is a 

 matter not easy to decide. Bethe (cited on p. 597, note 3) found (in the 

 crab) that the cell bodies are not essential to the performance of reflex 

 actions. In the case of the fibres of the posterior roots of mammals and 

 most vertebrates, there is no necessity for the nervous impulses to go 

 through the nerve cell at all, nor is their passage appreciably delayed 

 in traversing the ganglion. 10 It would, however, be of interest to 



1 Warrington {Journ. Physiol., Cambridge and London, 1898, vol. xxiii. p. 112) has 

 found chromatolysis to occur a certain time after section of posterior roots in the motor 

 cells of the anterior horn of the same side (chiefly of the postero-lateral group), and in a 

 few cells on the other side of the cord. He ascribes this result to the loss of afferent 

 impulses which normally impinge upon those cells. After section of an anterior root, 

 nearly all the cells of the corresponding segment of the cord show some sort of change of 

 the same kind. 



2 Schaffer, Abstract in Neurol. Ccnlralbl., Leipzig, 1894, No. 24. Numerous references 

 on this subject will be found in Warrington's paper, above quoted. 



3 Nissl, Allg. Ztschr. f. Psychiat., etc., Berlin, Bd. xlviii., 1., and liv. ; Centralbl. f. 

 Nervenh. u. Psychiat., Coblenz u. Leipzig. 1896, S. 544. Cf. also Lugaro. Riv. dipatol. nerv., 

 Firenze, 1897. 



4 Pandi, Abstract in Neurol. Centralbl., Leipzig, 1894, No. 24. 



5 Dehio, Centralbl. f. Nervenh. u. Psychiat., Coblenz u. Leipzig, 1895, Bd. vi. S. 113; 

 C. C. Stewart, Journ. Expcr. Med., N. Y., 1896, vol. i. No. 4 ; Marinesco, Presse mid., 

 Paris, 1897, No. 8 ; and Rev. gin. d. sc. pures et appliq., Paris, Mai 30, 1897. 



6 Goldscheider and Flatau, ' ' Pathol ogie der Nervenzelle," Fortschr. d. Med., Berlin, 1897. 



7 Goldscheider and Flatau, loc. cit. ; Chantemesse and Marinesco, Presse mid., Paris, 

 1898. For many other references on the effects of drugs, etc., on the nerve cell, see Barker, 

 "The Nervous System," 1899, chap. xxv. 



8 Sarbo, Neurol. Centralbl., Leipzig, 1895, No. 15, S. 664 ; Marinesco, loc. cit.; Gilbert 

 Ballet and Dutil, Arch, de neurol., Paris, 1897, tome iv. p. 430. 



9 Goldscheider and Flatau, loc. cit.; see also Turner, Brain, London, 1899, vol. xxii. p. 105. 

 10 This statement, due originally to Exner (Arch. f. Physiol., Leipzig, 1897, S. 567) 



has been confirmed as the result of a series of experiments upon the posterior roots of the 

 frog, which were performed at my request by B. Moore and H. W. Reynolds ("Internat. 

 Cong. Physiol., "Aug. 1898, Journ. Physiol., Cambridge and London, 1898, vol. xxiii. Suppl., 

 p. 56). They were careful to insure that the nervous impulses took the same path through 

 the cord to produce the excitation of the muscle, which was to serve as the signal, both when 

 the root was stimulated between the cord and the ganglion, and when the nerve was 

 stimulated beyond the ganglion, by cutting all the root bundles of the nerve employed 

 except one. A contrary result, namely, a delay of some 0"02 second in traversing the 

 ganglion, which was got by Wundt, was probably due to the fact that, on account of the 

 method which he employed, the nervous impulses in the two cases did not take exactly 



