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AN AMERICAN TEXT-BOOK OE PHYSIOLOGY 



same way by irrigation with a nutrient fluid. In one case, however, the cell 



was stimulated by electricity, while in the other no 

 stimulation was applied. During the time of the 

 experiment the cell which was nol stimulated re- 

 mained unchanged, while the stimulated cell went 

 through the series of changes exhibited in Fig. 83. l 



It followed that if these changes were really 

 significant of normal processes they should he found 

 in the nerve-cells of those animals which show 

 well-marked periods of activity, alternating with 

 periods of rest. To determine this, birds and bees 

 were examined, one set of preparations being made 

 from animals which were killed at the beginning of 

 the day, after a night of rest, and the other from 

 those killed at the end of the day, after a period of 

 activity. The cells from the latter animals were 

 found altered in a way similar to that following 

 direct stimulation of the axone. The changes were 

 demonstrated in the cells of the spinal ganglia of 

 English sparrows, of the cerebrum of pigeons and 

 cerebellum of swallows, and of the antennary lobes 

 of hees. These observations therefore support the 

 conclusions drawn from the appearances following 

 direct stimulation. 



( >ther observers 2 have obtained similar results. 



The motor cells of the spinal cord and cells of 

 the retina (dogs, Mann) have been added to the list 

 of those showing fatigue changes. In the sympa- 

 thetic ells of the rabbit, both Yas and Mann 

 found, after a short period of stimulation, a pre- 

 liminary swelling of the cell-body, anil the same 

 has been noted by Mann in the case of retinal cells 



Fig. 83.— Showing the changes \\\ flic dog. 

 in the form <>f tin- nucleus re- rm .. . - , . . , 



Buitingfromthedirecteiectricai I he application of these observations to changes 



Btimuiation of the living sym- j n t ] 1(l human nervous svstem has thus far been 

 pathetic nerve-cell oi a frog. 



The hour ofobservation is given made only in a casual way, but enough has been 



within each outline. The ex- already observed to make 'certain that the results 



perimeul lasted six hours and 



forty-nine minutes. \ control are applicable. 



cell treated during this time in u .,, , lJj.1j.j_i i i 1 Ml 



the same manner! except that U Will be noted that the changes above described 



it was not stimulated, showed follow variations in the amount of stimulation, the 

 no changes (Hodgi . ... . . , ,. 



nutrient conditions represented by the surrounding 



plasma remaining nearly constant. This latter, however, may undergo 



1 Hodge: Journal of Morphology, 1892, vol. vii. 



- Vas: Archiv fur mikroskopische Anatomie, 1892 ; Mann: Journal of Anatomy and Physiology, 

 1894. 



