658 Mr. W. C. Crawley on 
varying conditions and food supply, but in every case 
where the eggs came to maturity they were fs. 
On reading these papers it occurred to me that certain 
hitherto inexplicable phenomena mentioned in a paper 
some years ago (Crawley, 1900) might be explained by 
this fact of worker-eggs producing 9s. In 1896 I had a 
fair-sized colony of Lasius niger in captivity. This colony 
lost its queen through an accident, soon after the ants 
were established in their “ Lubbock” nest. The queen 
left a large quantity of eggs. To quote from the above- 
mentioned paper:—“I had at the time (August 1896) 
a solitary fertile Lasiws wmbratus queen, and finding that 
when placed in a pill-box with several Z. wigev Gs she was 
not attacked, I put her into the queenless nest of LZ. niger. 
.. . The little black ants received her eagerly, and she 
was very shortly established as queen of the nest... . 
During the year 1897 all the eggs and larvae left by the 
old niger queen hatched, the last brood of larvae having 
lived through the previous winter, but in that year and the 
next, though I paid careful attention to the nest, J was 
unable to trace any of the offspring of the L. wmbratus queen 
to maturity. As the 9s of LZ. wmbratus are bright yellow, 
and those of “. wiger are black, there is no possibility of 
confusing the two.” I may mention that I had observed 
the wmbratus queen lay eggs during 1897, and numbers of 
larvae lived through the winter of 1897-8, yet during 
1897 and 1898 all the ants (several hundred 9s) that 
reached maturity in the nest were L. niger. The niger 3s 
must therefore have devoured the wmbratus eggs or larvae, 
which is not surprising, since in 1899, when the wmbratus 
eggs were at last allowed to reach maturity, the young Gs 
were all killed and eaten, or divided among the larvae as 
food, by the niger 9s, within a few days of hatching. The 
queen used to spend a long time licking the eggs and 
larvae, an unusual proceeding for a queen ant. 
At the end of the paper I wrote that this acceptance of 
an alien queen by a queenless colony of another species 
might throw some light on the origin of slayery among 
ants. ‘This has now been demonstrated by Wheeler and 
Wasmann. 
In another paper (Crawley, 1909) before describing the 
second similar case of LZ. niger and umbratus of 1908, I 
recapitulated the principal facts of the 1896 colony, with a 
few important additions from my notebook :—“No eggs 
