12 S CAKOLDvE BURLIXG THOMPSON" 



in the winged adult caste of the first form, with primitive ances- 

 tral characters, and the adult caste of the second form, with 

 secondary modifications. 



The stiU later differentiation, at 3.75 mm. or less, of the general- 

 ized worker-soldier tA~pe into the prototype of the worker with 

 primitive structural characters, and the prototype of the highly 

 specialized soldier with many new features is again significant. 



The manner in which these castes have arisen in the indi\^dual 

 life cycle is perhaps indicative of the way they arose phylo- 

 genericaUy. The phylogeny of Leucotermes. table 3. may have 

 begun in a primitive ancestral reproductive type with a tendency 

 to throw off sterile or worker variations, perhaps mutants. This 

 tendency became fixed in the species, and the generalized repro- 

 ductive type and the generalized worker-soldier type occurred 

 side by side in every generation. Both types stiU kept the 

 tendency to vary, or mutate: as time went on. the generalized 

 reproductive type threw off the more specialized adults of the 

 second form, with short wing pads, etcetera, the type itself con- 



TABLZ 3 



Phytogeny of Leucotermes flacipes 

 Firs'. Form 



Second Form Third Form? 



! / 



Eeproductive Tyue Worker-Soldier Type 



Ancestral Reproductive Type 



