Hatai, Spinal Ganglion Cells of Rat. 479 



percentage deviations of the two diameters is unsatisfactory. 

 Although it may not be a conclusive test, yet remembering that 

 the spherical or nearly spherical cells should occur more frequently 

 either towards the negative side or at the mode than towards the 

 positive side, a determination of the relative frequency of such 

 spherical cells, or the cells with nearly equal diameters, may be 

 employed. Under the circumstances I think this is the only feasi- 

 ble method of testing this point. From an examination of original 

 data, it has actually been found that such spherical or nearly 

 spherical cells diminish with the increasing calculated diameter 

 and increase with a diminishing calculated diameter. Even 

 without any further test we cannot doubt from the theoretical 

 standpoint that the method of section diminishes the diameter of 

 the large cells, thus artificially increasing the frequencies of the 

 small cells. 



If this fact just mentioned is accepted, the conclusion follows 

 that the theoretical curves may be considered as satisfactory rep- 

 resentations under the circumstances and also may be considered 

 much truer representations of the frequency distributions of the 

 cell-bodies and nuclei than that shown by the actually observed 

 data. 



Since the curve of Type i has limited range in both directions, 

 we find from the constants that 



lower limit of range = 7.5844/t 

 and upper limit of range = 6o.9693/<, 



while the observed limits are 7.8 micra and 47.4 micra, respectively. 

 We see therefore that the theoretical lower limit agrees very closely 

 with the observed, while the upper limit in the theory is consider- 

 ably higher than that of the observed. But that this upper value 

 may not be entirely improbable is indicated by my previous work 

 ('02) on the spinal ganglion cells where I find cells in the fourth 

 cervical spinal ganglion of the adult albino rat as large as 52.7 

 micra. This figure just given is the average for the three largest 

 cells observed, therefore one or two individual cells must be still 

 larger. Nevertheless it is not necessary to assume that these cells 

 are the largest which could be found. This fact indicates that 

 there is a tendency at least to approximate the values given by the 

 theoretical curve. 



