52 Journal of Comparative Neurology. 



larged parts of the peripheral processes in consecutive turns of 

 a spiral usually touch each other, but consecutixe turns of the 

 spiral band itself are always separated by a space about of the 

 width of the band. 



In sections from material killed by alcohol, the peripheral 

 processes appear to be very slender and to be separated by very 

 large clear spaces. These spaces are really enormous vacuoles 

 which have formed within the processes themselves forcing the 

 protoplasm to one side. The strands of protoplasm between 

 these vacuoles thus present the appearance of very slender per- 

 ipheral process separated by large clear cells (the vacuoles). 

 In some material killed by Miiller's fluid, a few of the upper 

 peripheral processes and the cells to which they are attached 

 are much more deeply stained than the lower processes in the 

 same organ. (Plate II, Fig. 41). The protoplasm of such pro- 

 cesses always appears more poorly preserved — i. e. more shrunk- 

 en and more disintegated — than others. The only explanation I 

 can offer is that this appearance may be due to a different phys- 

 iological condition of these proceses or of the cells which 

 bear them at the time of death. I am certain that it is 

 not due to any morphological difference or to any difference in 

 function. In living material and in some material killed with 

 alcohol no essential difference whatever can be observed be- 

 tween cells or peripheral processes in different regions of a given 

 organ ; in material injected with methylene blue, the cells which 

 take the blue may lie in any part of the organ. I therefore 

 consider that a spiral organ is composed of but one kind of cell 

 and this cell is a nerve cell. 



Pigment is never present either in or around the peripheral 

 processes. It is sometimes found in and among the bodies of 

 the cells belonging to the spiral organs but never in any larger 

 quantities than are found associated with other structures in the 

 base of the epidermis. 



C. Distribution of the Spiral Organs. 



The number of the spiral organs is comparatively small. 

 They are most numerous on the head ; in the body itself they 



