No. 5S7] 



VARIABILITY AND AMPHIMIXIS 



659 



zygospores is at once suggestive that the group thus 

 close bred, is the more variable one. It is also of some 

 interest to note that the empirical range of variation for 

 the laterally formed zygospores, — with length from 49 m. 

 to 83 m., — is considerably greater than in the scalari- 

 form zygospores with lengths from 47 m. to 79 m. While 

 this is not a measure of statistical variability, it un- 

 doubtedly has a genetic value. 



TABLE I 



Length of 400 Zygospores from Spirogyra inflata (Vauch.), 200 pro- 

 Conjugation, ARRANGED IN CLASSES ACCORDING TO FREQUENCIES. 



Magnitudes in l/10m 

 Length of zygospores in microns. 



The general constants for the variability in the length 

 of the zygospore of the two groups are shown below 

 (Table II). It may be noted that the mean (M.) or aver- 



