5" I .1\TS. 



and productive nu-mbcTs of the community have the greatest diffi- 

 culty iu f riving tl:< ---elves. 2 



'Besides the mixed colonies <>f ants considered in this and the two pre- 

 ceding chapter-, there are a few cases of a very exceptional and problematic 

 character These are : 



i. A mixed colony comprising workers of Lasius nigcr and L. flavus found 

 by Adlerx ( iSoW' i in Sweden. 



_'. Tw<> small mixed colonies comprising workers of L. ncarcticus and L. 

 iinicncaints found near Rockford, 111. (Wheeler, 19051). 



3. Four small mixed colonies comprising workers of L. latifcs and L. amcr- 

 icuims found near Colebrook, Conn. (Wheeler, 1905;') . 



4. The small mixed colony of Leptothorax curuispinosus and L. longispinosus 

 mentioned on p. 495. 



5. A colony consisting of a male, two winged females and several workers 

 of Pseitdomyrma ftni'idula and several workers of Ps. elongata, found in a 

 hollow Cladinin culm in the Bahamas (Wheeler, 1905^). 



Adlerz believed that his mixed Lasius colony had been formed by dulosis, but 

 Wa-mann suggested that it was probably the result of an accidental alliance 

 lieiueen fertilized queens of different species. I am inclined to believe that 

 neither this nor the other colonies above enumerated arose in either of these 

 ways, but by the accidental irruption of one colony into the contiguous brood 

 galleries of another, followed by the pillaging and rearing of a number of alien 

 worker larvae or pupae. This is not dulosis, but as I have shown (p. 452), merely 

 one of its conditions. 



