STUDIES OF VARIATION IN INSECTS 221 



tion on basis of adult structures) show no more variation in wing 

 venation than those which have been so exposed. It is also 

 to be noted that our drones from cells show no more variation 

 than the free flying ones except in one particular. That is in 

 the presence among them, in the proportion of ii to 200, of 

 certain individuals whose front wings have a wholly abnormal 

 venation, of the condition of a sort of mutilation or monstrosity 

 of such a character as to prevent the full unfolding of the wing 

 and probably its use at all as a flight organ. As the fore wings 

 are the chief factors in the flight of bees, the hind wings being 

 attached to them by hooks, in large degree moved by them and 

 obviously auxiliary and subordinate to them, this variation prob- 

 ably produces a crippled individual quickly eradicated by nature 

 or perhaps purposely by the keen-eyed and thrifty workers. 

 At any rate we have never found such a crippled-winged drone 

 in any lot of individuals taken in the " drone catcher" (which 

 is a device fastened over the external opening of the hive and 

 which snares any drone that voluntarily attempts to issue from 

 the hive). For the rest of the variation the free-flying drones 

 show practically no less, and of course no more, modification in 

 venation than the ones taken from cells. 



Practically, thus, the same amount of variation exists in the 

 venation of the wings among free-flying drones and workers as 

 exists among individuals which have just acquired their imagi- 

 nal structure, which seems to mean nothing less than that this 

 variation as manifest, as considerable and in a few cases as 

 extreme as it is, and as common (/. e., occurring in numerous 

 individuals) as it is, is not sufficient to be of life and death value 

 in the struggle for existence. In the exposure of the bees to the 

 rigor of the factors which determine natural selection this varia- 

 tion in the skeletal framework of the wings, organs obviously 

 unusually important in the relation of the bees to the outside 

 world, does not afford a handle for the selective action of these 

 factors. 



It is of interest to note in passing the large importance at- 

 tached by entomologists to the venation characters in the sys- 

 tematic study of insects, especially those in which the venation, 

 as in the Diptera, Lepidoptera, and Hymenoptera (to which 



