LEE BARKER WALTON 107 



fore the differences of the two constants appear to have 

 no particular value so far as the present material is con- 

 cerned. 



The analytical constants necessary for the fitting of the 

 curves indicate that type IV curves may be used for each 

 method of conjugation. In lateral conjugation the 

 equation is 



1 + I y^^-9.5m tan -1(^/29.2687) 



29.26872/ 

 and in scalariform conjugation similarly the equation is 



(y2 \— 11.0943 



while the frequency polygons and the fitted curves illus- 

 trate the conditions diagramatically. 



2. Comparative Variability in the Diameter of the 



"Zygospores 



The class range adopted in the frequency distribution 

 for diameters of the two groups of zygospores was one 

 micron, measurement being made at the maximum 

 diameter. An inspection of the distribution shows at 

 once the greater concentration of the variates in scalari- 

 form conjugation, and thus their smaller variability. In 

 considering the general constants of variability based on 

 the diameters it is to be noted that the means (M.) do not 

 differ, as we found when considering length. The 

 standard deviation (o-) and the coefficient of variation 

 (C. V.) once more demonstrate the greater variability of 

 the laterally formed zygospores. The values of the con- 

 stants for skewness (Sk.) are not sufficient, however, 

 when considered with the probable error"", to be of im- 

 portance. The frequency polygons illustrate conditions, 

 although no curves have been fitted. 



^The following formulx as the basis of the probable errors, may be noted: 



PEa = .67449 



\ 4M^ I yfln L \ 100/ J 



P£sk. = .67449 a/— / Vl + 3(Sk.)-. 



