VARIATION AND MUTATION 



155 



able. The nature and results of fertilization and ajuphiinixis 

 are treated in Chapter XIII. 



But parthenogenetically produced individuals (that is, 

 young born from unfertilized eggs — as the honey-bee drones, 

 certain wliole generations of various gall flies, saw flies, ai)hids, 

 etc., etc., regularly are) also vary. 

 In the case of male bees, male 

 ants, female aphids, etc., etc., the 

 individuals differ quite as much as 

 do individuals of the same species 

 of bisexual parentage. Comparing 

 the variation in drone bees (par- 

 thenogenetically produced) as com- 

 pared with that of the workers 

 (from fertilized eggs), we find that 

 this is true. The organs examined 

 for variation in these series of bees were the wings, organs 

 used by both drones and workers, and having no immedi- 

 ate relation either structurally or physiologically to the differ- 

 entiation of those two castes or kinds of individuals of the 

 honey-bee species. The workers are " incomplete " only in that 

 most of them are infertile: in no other structural or physiological 

 feature of their makeup are they less "complete" than the 

 drones. They are indeed distinctly the more speciahzed of 



Fig. 93. — Fore and hind wings 

 of honeybee (drone), sliowinj? 

 normal venation. (After Kel- 

 logg and Bell.) 



Fig. 94. — ^Part of costal margin of hind wing of honeybee, much magnified to show 



hooks. (After Kellogg and Bell.) 



the two, and according to one of the early Darwinian canons of 

 variation might be expected to differ more than the drones. 

 But the drones are males and, according to another commonly 

 accepted belief, this is the explanation for a larger variation on 

 their part, if such larger variation occurs. As a matter of fact, 

 it does. The drones, in all the many series studied, sliow mark- 

 edly more variation in the venation of the wings than do the 

 workers, while they show quite as nnich variation as the work- 

 ers in the number of the hooks which liold the two wings togetlier 

 in flight. (See Figs. 93 to 96.) Botli these characters, i.e., 

 wing venation and wing hooks, are not so-called " male diar- 



