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XXIX. Heperiments on the Formation of Colonies by Lasius 
fuliginosus @ 9. By Horace Sv. J. K. Donis- 
THORPE, F.Z.S., and W. C. CRAWLEY, B.A. 
[Read November 15th, 1911.] 
IN a paper read at the meeting of the Entomological 
Society of London on December 7th, 1910, Donisthorpe 
stated that it was our intention to carry out experiments 
with queens of Lasius fuliginosus and observation nests of 
L. wmbratus. This we have now done, and the following 
paper shows the results of our investigations. Our object 
was to find out if small wmbratus colonies would accept 
Juliginosus 22 as their queens. We may state at once 
that in this we have been quite successful. It may, how- 
ever, perhaps be as well to recapitulate the facts that led 
us to make this inquiry, before giving the details of our 
experiments. 
In 1908 de Lanoy published the fact that he had found 
in 1904 at Knoche-sur-Meér in Belgium, a large colony of 
Lasius fuliginosus in which workers of Z: miztus (a sub- 
species of wmbratus) were present, and that subsequently 
in 1906 he had found several other colonies of fuwliginosus 
containing mixtus workers. 
Forel and Emery then expressed the opinion that the 
meaning of the presence of these strange workers was 
that a fertile 2 fuliginosus had entered a nest of mixtus 
to found her colony; that she had been accepted by the 
workers of the latter, and that the mixtus 2? had either 
died or been killed. In the course of time, the /wliginosus 
brood being reared, the mzxtus workers had died off, and 
the few found in the nest were the last survivals of the 
original mixtus colony. 
In 1909 Wasmann accepted this interpretation, and 
pointed out that subterranean nests of mixtus and wm- 
bratus are frequently found at the foot of trees close to the 
nests of fuliginosus, and that he had often seen workers 
of these yellow Zasiws among the black fuliginosus. He 
urged those naturalists who have the opportunity to 
make experiments with these ants. 
TRANS. ENT. SOC. LOND. 1911.—PART IV. (JAN.) 
