Formation of Colonies by Lasius fuliginosus. 671 
to the wmbratus nest. Here she was at once attacked by 
five ants, so was removed and placed in a separate chamber 
with three wmbratus to allow her to get rid of the fult- 
ginosus odour, but she was still attacked by one of the 
three. As she was again attacked the following day on 
being restored to the nest, no further attempt was made 
to induce the colony to take her back. 
In time the abdomens of the two 2? began to become 
distended, and on the 17th there was a batch of about 
twenty eggs. These eggs were added to from day to day, 
and the queens’ bodies became enormously distended so 
that they appeared like semi-transparent whitish sacs, 
with narrow bands of black. 
On August 9th the eggs began to hatch, and the larvae 
grew rapidly in size and numbers, At the moment of 
writing (November 13th, 1911) there is a large number of 
half-grown larvae, which should, all being well, pupate 
early next spring. 
Several times during the past summer L. niger pupae 
have been given to this colony, to try and ascertain 
whether the wmbratus 83 had any friendly instincts re- 
maining towards the species in a colony of which they, 
in all probability, began their existence. The pupae 
were always readily carried in, but seemed to be left too 
long before being opened, with the result that the $9 
were dead or crippled when they did emerge. However, 
several lived for some time, but seemed to be bullied 
by the wmbratus. There are now two niger $9 in the 
nest, apparently in a perfectly healthy condition, and 
unmolested by their hosts. 
It would have been more satisfactory in some ways 
if this paper had been delayed until the larvae had 
pupated and hatched. But as we have now proved for 
the first time the hypothesis that LZ. fuliginosus 22 can 
be accepted by colonies of LZ. wmbratus and bring up their 
young with the aid of their hosts, it seemed of greater 
importance to put the facts on record at once. 
Crawley has already demonstrated (1909) that queens 
of L. umbratus (the other British parasitic species of this 
genus) do not lay eggs until the year following impreg- 
nation. We have now shown that is also the case with 
L. fuliginosus, as the 2 § fertilised in July 1910 did not 
lay till June and July 1911. 
The queens of both these species are smaller in com- 
