No. 2.] CHANGES IN NERVE CELLS. 97 



we should know or at least have the key to learn all of nerve 

 physiology, from the action of the nervous mechanism (?) in an 

 amoeba's protoplasm, through the entire animal series, to the 

 activity of the human brain. 



A certain fascination attaches to the study of the nerve cell, 

 because it is associated with the higher activities of life. Sensa- 

 tion, intelligence, volition, are in some way dependent upon the 

 integrity and healthful action of the cells of the brain, and 

 many have been the theories, without foundation, concerning 

 the working of the soul within its "material sanctuary." In 

 fact, so many ideas, thoroughly unscientific in character, have 

 appeared in this field, that it is with some slight danger that 

 one undertakes to work in it even now. It is still a living 

 sentiment that a man who meddles much with the brain is 

 seeking the " seat of the soul," as De Cartes actually did, and 

 as Charles Bell, nearly two hundred years later, was accused of 

 doing. As a friend remarked to the author on beginning the 

 work, "You will find no changes in nerve cells corresponding to 

 those which take place in a gland. Changes are demonstrable 

 in gland cells, because these produce a material secretion ; you 

 should find changes in muscle, because its action results in 

 mechanical work ; but the case of a nerve cell is different, its 

 secretion is consciousness, a thing outside the equation of con- 

 servation of physical energy." As he put it, "The action of 

 nerve cells is in a fourth dimension of space." However, tran- 

 scendental objections to the contrary, the problem is simple 

 enough. A nerve cell is certainly a minute speck of three 

 dimensional, material protoplasm. Compared with the cells of 

 other tissues it is often large, and compared with them, too, it 

 is definitely characterized. A nerve cell is in general made up 

 of a mass of granular protoplasm, enclosing a large nucleus, 

 which exhibits a delicate reticulation and contains a prominent 

 nucleolus. In a spinal ganglion cell, for example, all these 

 characters are much more prominent than in any of the gland 

 cells wherein functional changes have been observed. If a 

 nerve going to a gland be stimulated, the cells become active, 

 granules pass out of the cell protoplasm into the secretion, and 

 the cell nuclei often undergo marked changes of appearance. 

 If a nerve going to a ganglion be stimulated, if the cells have 

 any function, why might it not be possible to demonstrate sim- 



