EVOLUTION IN NATURAL SCIENCE 13 



degenerate males, so that this ant is in absolute dependence 

 upon the workers of the wood ants, amongst whom it lives. 

 This parasitic ant must be descended from a genus that 

 possessed workers and once led an independent existence. 



As an instance of discontinuity of variation, the lecturer 

 showed a photograph of the males of the Formicoxenus, 

 that closely resemble workers, and they are the more 

 remarkable because no trace can be found among ants of 

 any gradual transition from the male to the female 

 worker. 



The last series of photographs showed a number of strange 

 guests among the termites, belonging to various families of 

 beetles and diptera. By accommodation to the way of life 

 among the termites, new systematic families have arisen 

 (Termitoxeniidce and ThaumatoxeniidcB) in exactly the 

 same way as they arose among the beetles (e.g. Clavigeridce, 

 Paussidce, etc.) in consequence of accommodation to the 

 myrmecophile life. The last photograph showed a coloured 

 longitudinal section of the Termitoocenia Assmuthi, a very 

 small fly living with the white ants of the East Indies. 



The lecturer closed his display of photographs with 

 approximately the following words : 



I wish to draw your attention to the fact that 

 accommodation to the life of ants and white ants 

 or termites has in all probability led to the forma- 

 tion of new species, genera, and families among 

 their guests, which belong to very various families 

 and orders of insects. In some cases (Thauma- 

 toxena) the characteristic marks have been so 

 completely altered by accommodation that it is 

 scarcely possible for us to determine to which order 

 of insects this strange creature belongs. In other 

 cases (Termitomyia) the whole development of 

 the individual is modified in such a way that it 



