234 



KENJI NITTONO 



from the middle part of the ganglion at intervals of every five 

 sections, were measured. 



The measurement of the ganglion cells is somewhat difficult 

 on account of the irregularity of the outline of the cell body. 

 In the case of both the cell body and the nucleus the two maxi- 

 nunn diameters at right angles to each other were those measured. 



Dicjmtjtyrs >n micra 

 70 



Body weight (oDservedigms. 

 280 



t20 * 



=P=n- 80 2 



iOO 350 



Age-Ssys 



Chart 1 Based on table 3 and giving, on age in days, the diameters of the 

 largest cell bodies in the gasserian ganglion of the albino rat (upper solid graph) 

 and their nuclei (lower solid graph). Ordinate values in /x at the left. Also the 

 observed body weights (upper broken graph), the ordinate values for which 

 are at the right and the computed brain weights (lower broken graph), the 

 ordinate values for which are at the extreme right. 



In the case of the cell bodies, the longitudinal diameter was 

 the one which passed through the long axis of the cell, and the 

 transverse diameter was taken at right angles to this on a line 

 passing through the middle of the nucleus. Similarly, in the 

 case of the nucleus, the longitudinal diameter was taken through 

 its longest axis and the width was at right angles to this line and 

 through the middle of the nucleus. The 'computed' diameter 

 which appears in table 3 and those that follow is obtained in 

 each case by taking the square root of the product of the long 

 by the short diameter. 



The fibers were cut, as nearly as possible, at right angles to 

 their long axes, which made the cross-section of a myelinated 



