550 S. WALTER RANSON 



ganglion cells, they do not exclude the possibility that transitory 

 changes may occur during the first week or two after the lesion. 



This question of the variation in external form of the spinal 

 ganglion cells needs further study. Levi ('07) and Huber ('13) 

 have shown that cells with fine processes ending in bulbs are to 

 be found in the spinal ganglion during late foetal life and shortly 

 after birth. The early appearance of these structures is an 

 important fact to bear in mind in estimating their significance, 

 and evidently points in the opposite direction from the evidence 

 presented in this paper. But this much is clear, that under 

 pathological conditions and in transplanted ganglia simple unipo- 

 lar spinal ganglion cells become transformed into complex multi- 

 polar cells, due to the sprouting of new processes from the cell 

 body and axon, and that these complex cells are very similar to, 

 if not identical with, those found in varying mmibers in normal 

 ganglia. It is also clear that these new-formed processes can 

 later disappear and the cell again be transfoniaed into the simple 

 unipolar type. In this way it is demonstrated that the form of 

 the spinal ganglion cell is not stable and fixed, but is capable of 

 undergoing m.arked alteration in a .short space of time. It is 

 probable that the similar complex cell types seen in normal ganglia 

 in such varying nmiibers are not characteristic of this or that 

 functionally distinct group of neurones, but rather a transient 

 expression of the physiological condition of the neurone. 



Just what the factors are which bring about such changes in 

 form is here left unmentioned because we have no adequate 

 means for fonning a conception of them, and what theorizing 

 has been done on the subject has only tended to obscure the 

 essential fact that the spinal ganglion cells readily undergo strik- 

 ing changes in form. 



