STUDIES OF VARIATION IN INSECTS 243 



are 23 and 24 (see p. 232) that 175 individuals have both right 

 and left wing with either 23 or 24 hooks, while 123 have either 

 the right or left wing with less than 22 or more than 25. Of 

 these the cases where both wings have under 22 are 14, and 

 both over 25 are 13, thus making a total of 27 cases out of 

 123 where the second member of a pair is also as marked in 

 variation as the first. 



In the lot of 200 drones taken from cells in another hive, the 

 modal numbers being 23 and 24, 48 individuals have both right 

 and left wings with either 23 or 24 hooks, while 74 have either 

 the right or left wing with less than 22 or more than 25. Of 

 these the cases where both wings have under 22 are 10, and 

 where both have over 25 are 5 thus making a total of 15 cases 

 out of 74 where the second member of a pair is also as marked 

 in variation as the first. 



In the lot of 300 workers from the laboratory hive, it is plain 

 from the frequencies of the various classes (see p. 233) that 20, 

 21, 22 and 23 are the more usual numbers of hooks. In 201 

 individuals neither wing has fewer than 20 nor more than 23 

 hooks, in 98 individuals either the right or left wing has under 

 20 or more than 25. Of these both wings have under 20 hooks 

 in 10 cases and both over 23 in 5 cases thus making a total of 

 15 in which the second member of the pair is also as marked in 

 variation as the other member. In only one case has one wing 

 under 20 and the other over 23 ; there is one case of 20-26, one 

 of 18-23, and two of 19-23 in the lot. 



It is certainly surprising to find such relatively small bilateral 

 and metemeric correlation in these insect variations when one 

 recalls the immense amount of bilateral and metemeric correla- 

 tion (often in great detail) which characterizes the class of in- 

 sects to-day, a correlation which we presume to have come 

 about through the known evolutionary factors. 



Summary. To sum up in few words the conditions noted to 

 exist in the honey bees, we find : (a) that in certain impor- 

 tant structural characters, viz., the venation (skeletal frame 

 work) of both fore and hind wings and the costal hooks which 

 hold, in flight, the hind wings to the fore wings, there is a 

 marked degree of variation which we can confidently term 



