DONISTHORPEA. 235 



and in its colouring between the two extremes. One with a reddish 

 tinge, another of the pale yellowish brown kind, and a third of the 

 dark sepia brown, precisely similar in its colouring to Mr. Bignold's 

 (sic) specimens, from a very strong and long-established colony of 

 umbratus in my garden. This colony for very many years has 

 produced no females, males having been developed in their 

 thousands, nay, tens of thousands, but not a single female having 

 come within view. In 1882, however, the species swarmed in the 

 Vicarage, and must have come up through the foundations in some 

 mysterious way. The males and females were accompanied by the 

 workers, who seem to exercise over them a singular and controlling 

 power. All the females were of the dark brown type with a fine, 



Fig. 86. D. mixto-umbrata Q with patches of algae 

 on body and legs. 



silky sheen, and the pubescence I find more marked and clearly 

 defined in some specimens than in others." 4 



By " pubescence " on the tibiae, etc., Farren- White means the 

 outstanding hairs. It is evident that though the typical forms are 

 quite distinct, these intermediate varieties are more confusing and 

 difficult to deal with. 



On August llth, 1912, when at Weybridge in company with 

 Professor Wheeler, we found two colonies of this variety, very 

 many of the ants of both being infested with a curious dark brown 

 warty growth in patches on parts of the body and legs this Wheeler 

 thought might be a fungus which was unknown to him. 



I kept a number of these ants in captivity, and added uninfected 

 workers of umbrata from other localities ; the growth however did 

 not increase nor spread to the new ants, but rather seemed to 

 decrease. I sent some of the infested ants alive, and others in 

 spirit, to Dr. Baylis Elliott, and she considered the patches were 

 colonies of unicellular organisms growing on the outside of the 





