Hatai, Spinal Ganglion Cells of Rat. 485 



1. Pycnomorphic cells, those cells which appear darker owing 

 to a stronger affinity to the staining reagents. The cell-outlines 

 are irregular. Such cells are usually small in size. 



2. Apycnomorphic cells, those cells which appear pale owing 

 to weaker affinity for the staining reagents. The cell-outlines are 

 regular, being either spherical or oblong. Such cells range from 

 small to large and include those which are made artificially smaller 

 owing to the method of sectioning. 



Attention is called to the fact that the above classification does 

 not modify our views concerning the existence of three histological 

 varieties of cells recognized in the spinal ganglion (see p. i) but 

 merely shows that these varieties do not distinguish themselves 

 by their diameters in such a way as to form separate groups under 

 this method of examination. 



ON THE CORRELATION BETWEEN CELL-BODY AND NUCLEUS. 



The intimate physiological relations existing between the cell- 

 body and the nucleus suggest that there may also exist a definite 

 size or mass relation between these two structures. Generally 

 speaking in the growing spinal ganglion cells (Hatai '01), the 

 cell-body grows much faster than the nucleus. It was my object 

 to determine this mass relation, between the cells and nuclei and 

 if possible to find some mathematical expressions by which such 

 relation could be concisely stated. 



The correlation table (Table II, p. 490) furnishes us all the 

 data necessary to determine such a relation. The table shows the 

 range of variates in one character corresponding to that in the 

 other. The coefficient of correlation would be then a numerical 

 expression of the occurrence of the several values of x in one 

 character in association with the several values of y in the other. 

 Pearson gives the formula for obtaining the coefficient of correla- 

 tion in the following form: 



2" (x. y.) 



r = 



n. -J, (7, 



Using the above formula, the value of r (coefficient of correla- 

 tion) was found to be 0.8616 ±0.0055. This shows that the size 

 of the cell-body is highly as well as positively correlated with the 

 size of the nucleus. Therefore we infer that the larger cell-body 

 is associated with larger nucleus, and vice versa. We can also 



