BULLETIN 



American Museum of Natural History. 



Volume XXIII, 1907. 



59. 57, 96: 11.51 



Article I. — THE POLYMORPHISM OF ANTS, WITH AN 



ACCOUNT OF SOME SINGULAR ABNORMALITIES 



DUE TO PARASITISM. 



By William Morton Wheeler. 



Plates I-VI. 



The study of sex determination among organisms — a subject obviously 

 included under the greater problem of the origin of variation, since sexual 

 dimorphism is the most striking and constant form of intraspecific variability 

 both in animals and plants — and the related but much more restricted prob- 

 lem of polymorphism, have of late attracted the attention of many biologists. 

 A perusal of some of the literature bearing on these subjects, however, has 

 convinced me that the simplicity of the questions involved may have been 

 overestimated. That this is especially true of polymorphism as manifested 

 in the social insects, will, I believe, be evident from a consideration of the 

 facts recorded in the following paper. At any rate, it will not be a difficult 

 task to show that we are still very much in the dark concerning the funda- 

 mental causes of the differentiation of one sex into several distinct phases, 

 and, while it may be urged that the problem of polymorphism as it is pre- 

 sented by the social insects, may be more complicated than that of sex, on 

 purely a priori grounds the opposite view would seem to be the more prob- 

 able, for polymorphism is undoubtedly not only a more restricted phenome- 

 non but one of much more recent phylogenetic and ontogenetic development, 

 and hence presumably dependent on conditions both more specialized and 

 more amenable to observation and experimentation. While the observa- 

 tions recorded in this article suggest both the need of experiment and some 

 of the points at which the problem is open to this method of investigation, 



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