1907.] Wheeler, The Polymorphism of AnU. 31 



one hand, and normal females on the other, are of very rare occurrence. 

 Wasmann ^ has, however, seen one colony in which "all possible transitions 

 between normal workers and females were represented. The pseudogynes 

 of this colony may be divided according to their stature into micropseudo- 

 gynes, mesopseudogynes and macropseudogynes. Among the mesopseudo- 

 gynes there are numerous transitions to the workers, but never Avith vestiges 

 of wings; among the macropseudogynes there are ergatoid and gyngecoid 

 forms, of which the former sometimes bear distinct vestiges of Adngs on the 

 relatively short, narrow mesothorax, while the latter often possess perfectly 

 developed but rather short wings on the exceedingly broad mesothorax, 

 and in addition similar posterior wings on the metathorax. The latter 

 forms may be designated as macronotal, brachypterous females, in con- 

 tradistinction to the normal stenonotal, macropterous females." 



As Wasmann's researches progressed he became more and more im- 

 pressed with the fact that the parasitism of the Lomechusini and the occur- 

 rence of the pseudogynes stood in a causal relation to each other. A five 

 years' statistical study of 410 colonies of Formica sanguinea near Exaten in 

 Holland finally led him to maintain the following theses:^ 



"a. The regions in which pseudogynes occur always coincide with 

 Lomechusa regions. 



"b. The colonies containing pseudogynes are always the centers of 

 Lomechusa regions. 



"c. Pseudogynes are never found in sanguinea colonies outside the 

 Lomechusa regions. 



"d. In colonies in which Lomechusa lives merely as a beetle (t. e., in 

 the imaginal instar), pseudogynes are never developed, but only in such as 

 have for years been rearing the larvse of Lomechusa.'^ 



These results were found to hold good also for other European localities. 

 He found, moreover, a similar causal connection between the occurrence 

 of pseudogynes of F. rufa and the beetle Atevieles pubicollis, F. rufibarbis- 

 and A. paradoxus, F. fusca and A. emarginatus. In the case of Atemeles, 

 of course, the pseudogynes are restricted to the ants among which its larvae 

 are reared and do not occur in the Myrmica colonies with which it merely 

 hibernates. The Formica colony is therefore analogous to the definitive 

 host of dioecious, non-social parasites like the tapeworm, while the Myrmica 

 colony corresponds to the temporary host of this entozoon. 



As early as 1895 ^ Wasmann undertook to explain the origin of the 



1 Ueber ergatoide Weibchen und Pseudogynen bei Ameisen. Zool. Anzeig., No. 536, 1897, 

 p. 252. 



2 Neue Bestatigungen der Lomechusa-Pseudogynen-Theorie. Verhandl. deutscli. Zool. 

 Gesell., 1902, p. 100. 



3 Die ergatogynen Formen, etc., loc. cit. 



