130 journal of Comparative Neurology and Psychology. 



It should be stated that, while Lugaro used a variety of mammals, 

 Cox confined his studies to the ganglia of the rabbit and Warrington 

 and Griffith used only the cat. It is very probable that this is 

 in part res2)onsible for the fact that there is not perfect agreement 

 in results. 



TABLE I. 

 Types of Cells in the Second Cervical Ganglia of the Cat. 



Warrington and Griffith. 



Lugaro. 



Cox. 



Size. 



Clear cells !TypesI&II Type I 35-100 



Obscure cells Type III Small cells 10-56 



Coarsely granular cells . . . .' Type IV , Type II (?) | 35-50 



Smallest clear cells ! Type IV 10-25 



Relative 

 Number. 



25.% 

 68.1% 

 4.3% 

 1.9% 



In considering such a classification the question arises as to just 

 what significance is to be attached to the grouping adopted. Do 

 the cells belonging to such a group retain permanently their special 

 characteristics; or may a cell pass from one tyj^e into another, as 

 physiological conditions change ? In other words, does a type repre- 

 sent a group of cells anatomically distinct or only a set of cells 

 which happen to be at the moment of fixation in the same physio- 

 logical phase ? Lugaro is of the opinion that his five types of cells 

 must be considered as specifically distinct from an anatomical point 

 of view. But the study of the reparative changes in the ganglion 

 after section of the nerve has led me to regard it as extremely 

 probable that the arrangement of the Nissl granules is quite as 

 much an expression of the functional phase of the cell as of its 

 anatomical type. Thus, in the repair following chromatolysis the 

 cells can be followed as they pass in the course of a few days from 

 one well-marked type of finely granular cells into another well-marked 

 type of coarsely granular cells. The contrast between these two 

 states of the same cell is much greater than that between the cells of 

 Lugaro's Types I and II. 



We shall, therefore, not attempt to classify the spinal ganglion 

 cells according to the arrangement of the tigroid substance alone, 



