STUDIES OF VARIATION IN INSECTS 



235 



had torn wings) is graphically shown in the frequency polygon 

 on p. 234 (hg. 25). 



The range is from iS to 25, the mean 21.4, the mode 21 and 

 22 (these two numbers of the same frequency), the standard 

 deviation 1.462 and the coefficient of variation 6.8. 



Fig. 26. Frequency polygon of variation in number of costal hooks of the 

 left hind wings of 50 worker honey bees taken from hive No. 10 at one time ; 

 mean 22.1 ; index of variability 1.36; coefficient of variation 6.15. 



From another hive on Stanford University campus were 

 taken a lot of 50 workers and a lot of 50 drones. The varia- 



Fig. 27. Frequency polygon of the variation in number of costal hooks of 

 the left hind wings of 48 drone honey bees taken from hive No. lo at one time; 

 mean 21.1 ; index of variability 2 ; coefficient of variation 9.53. 



