468 DAVID H. DOLLEY 



computations were made by aid of the slide rule but are thought 

 to be sufficiently exact for this comparison. There is nothing 

 to distinguish Experiment Shock 37 from any of the other experi- 

 ments in the matter of its range in size of individual cells. Finally, 

 the average of the individual coefficients for a total of 250 cells 

 (table 4) is 11.696. The mean of the average coefficient figures 

 in table 1 for the same experiments is 11.469. These facts would 

 seem sufficiently to answer a possible objection that the average 

 of individual volumes should have been used rather than the 

 average of individual dimensions. Practically, one comes to 

 the same result whatever the method of averaging. 



Considering further the possibilities of variation dependent 

 upon the nature of the calculations, it will serve to emphasize 

 the constancy of the coefficient figures to point out how small 

 differences in diameter or volume figures are magnified in the 

 resulting coefficient figures. Thus, as a single example, it would 

 only take an increase in the nuclear volume of forty cubic micra 

 in Experiment Shock 37, whose coefficient figure is the most 

 widely variant by average measurements, namely 12,37, to 

 inake the resulting coefficient 11.82, which in any estimation 

 of an average calculation would be a slight variation. It must 

 be remembered also that here one is dealing with cubic contents. 

 Small differences in the diameters, particularly the transverse 

 diameters, become so much the more magnified. One micron 

 less for the transverse diameter of Experiment Shock 37 would 

 reduce the nucleus-plasma coefficient from 12.37 to 10.86. 



Next, of the purely technical factors of variation, this same 

 experiment actually illustrates what is probably, next to deviation 

 from a diametral plane of section, the most important one. 

 This is the determination of the longitudinal diameter of the 

 cell body. The rule followed was to measure to the point where 

 the dendrite becomes a constant size. When one has measured 

 hundreds of cells, the determination of this becomes a fair con- 

 stant for that measurer. Yet even then it occurs that certain 

 dogs have exceptionally slender cells; there is no definite tran- 

 sition from cell to dendrite, but the change is most gradual, so 

 that the measurement is an approximation. Experiment Shock 



