No. 2.] CHANGES IN NERVE CELLS. 109 



condition of my research is that furnished us by Max Schultze 

 (75) and confirmed later by the work of Kupffer (31), Boveri (6), 

 and Joseph (27). My preparations do not in any way support 

 the tubular theory which Nansen (56) has drawn from his obser- 

 vations upon the nerves of invertebrates. This conception is 

 that the axis cylinder consists of a bundle of fine fibrils floating 

 in a plasma. All fibrils arise as outgrowths of nerve cells (29, 

 p. 51), and are seen continued into the cell as the fibrillar reticu- 

 lum of the cell-protoplasm. In the cell, and to some extent in 

 the nerve fibre, granules occur between the fibrils. Those in 

 the fibre are exceedingly fine, in the cell are generally coarse 

 and so densely packed as to hide the reticulum altogether. We 

 have thus at least the two things necessary for a nerve mechan- 

 ism : the fibril to conduct, and, in close touch with this, a gran- 

 ular substance, changes in which may serve to originate or 

 modify the nerve impulse. In addition we have a nucleus and 

 nucleolus, proportionally as large or larger than the nucleus of 

 a growing ovum. Thus all the elements of cell structure, 

 nucleus, granulation, reticulum, are highly developed in the 

 ganglion cell. May we not then expect to find changes like 

 those of an ovum in the nucleus, and changes in the granular 

 contents like those occurring in gland cells .-' We have no 

 ground to expect to find any change in the fibrillae themselves. 



A good deal of work has been misdirected to the study of 

 so-called pathological changes in nerve cells. I say misdirected, 

 because until normal processes are known it is clearly impos- 

 sible to draw the line between what is normal and what is 

 abnormal. 



A careful statement of pathological changes is given by Ober- 

 steiner (59, pp. 112-116 and 125-129). The gross process of 

 degeneration in a nerve fibre is comparatively simple and too 

 well known to require description. For the ganglion cell patho- 

 logical changes are exceedingly varied. Of the nine varieties 

 described by Obersteiner I shall at present file a word of caution 

 against two. Simple atrophy, he says, begins by shrinkage with 

 loss of structure of the nucleus, its outline becoming jagged, 

 followed by shrinkage of cell, disorganization of processes, and 

 finally ending, it may be, in the disappearance of the entire 

 neuron. Again, vacuolation is given as a pathological change 

 in cases of inflammation. Although Obersteiner is careful to 



