CENTRAL NERVOUS SYSTEM. 



629 



unstimulated spinal ganglion, a picture like that represented by Figure 157 is 

 obtained. 1 



The sections indicate that the cytoplasm together with the enclosed nucleus 

 arid nucleolus as well as the nuclei of the enclosing capsule of the cell, have 



FIG. 157. Two sections, A and B, from the first thoracic spinal ganglion of a cat. B is from the gan- 

 glion which had been electrically stimulated through its nerve for five hours. A, from the correspond- 

 ing resting ganglion. The shrinkage of the structures connected with the stimulated cells is the most 

 marked general change, n, nucleus ; n. s, nucleus of the capsule ; v, vacuole ; X 500 diameters (Hodge). 



all suffered change by this treatment. The stimulus was applied for only 

 fifteen seconds of each minute, the remaining forty-five seconds being given to 

 rest. In this way the cells here figured had been stimulated over a period of 

 five hours. The nuclei of the sheath are flattened, the cytoplasm somewhat 

 shrunken and vacuolated. With osmic acid the nuclei of the stimulated cells 

 stain more darkly and the cytoplasm less darkly than in a resting cell. The 

 nucleus is shrunken and crenated, and the nucleolus is also diminished in size. 

 In the first experiments the attempt was made to demonstrate a measurable 

 change within the nerve cell-bodies as the result of stimulation. Assuming the 

 nuclei of these cells to be approximately spherical, and calculating their vol- 

 ume as spheres, the shrinkage amounted to that shown in the following table : 

 1 Hodge : Journal of Morphology, 1892. 



