1907.] Wheeler, The Polymorphism of Ants. 57 



(24) The merm,ithergate, which has been described in detail in the pre- 

 ceding pages, is an enlarged worker, produced by Mermls parasitism and 

 often presenting dinergate characters in the thorax and minute ocelli in the 

 head. 



(25) The phthisergate, which corresponds to the phthisogyne and 

 phthisaner, is a pupal worker which in its late larval or semipupal stage has 

 been attacked and partially exhausted of its juices by an Orasema larva. It 

 is characterized by extreme stenonoty, microcephaly and microphthalmv, 

 and is unable to pass on to the imaginal stage. It is in reality an infra- 

 ergatoid form. 



(26) The gynanclromorph is an anomalous form in which male and 

 female characters are combined in a blended or more often in a mosaic 

 manner. 



(27) The ergatandromorph is an anomaly similar to the last but having: 

 worker instead of female characters combined with those of the male.^ 



2. The Views of Some Previous Authors on Polymorphism. 



In their attempts to explain polymorphism authors have not, of course^ 

 taken all of the above enumerated phases into consideration, but have been 

 content to include only the typical and perhaps a few of the atypical and 

 pathological phases. And it is clear that if the main phases could be ac- 

 counted for, the rarer and less important deviations would present few dif- 

 ficulties. I shall endeavor to show, however, that some of these singular 

 forms may shed at least a few rays of light on the problem of polymorphism. 



The social insects have held an important place in discussions of evolution 

 and heredity ever since Darwin called particular attention to these animals 

 in the eighth chapter of the 'Origin.' In later years they assumed even 

 greater prominence in the controversies between the Neolamarckians and 

 Neodarwinians concerning the efficacy of natural selection. This was 

 unavoidable, for polymorphism would seem to be of such a nature as to 

 afford a test of the validity of any hypothesis bearing on the inheritance or 

 noninheritance of acquired characters as well as of any hypothesis concern- 

 ing the rdle of preformation, or epigenesis, in the development of organisms. 

 As it will be impossible in this place to present a detailed history of the 

 subject or to dwell on all its wider implications, I shall confine myself mainly 

 to the views which were championed by Weismann and Herbert Spencer 

 respectively in their well-known controversy in the 'Contemporary Review', 



* For an account of the known cases of this and the preceding anomaly among ants see my 

 paper: 'Some New Gvnandomorphous Ants, with a Review of the Previously Described Cases ' 

 Bull. Am. Mus. Nat. Hist.. XIX. 1903, pp. 653-683. U figs. 



