Vi8 Ma HAs: Hx. Donisthorpe’s Observations on 
small, a rufa §, some 50 fusca 33, and a number of 
cocoons. The whole of the nest was most carefully dug 
up and examined, but no trace of a fusca 2 could be found. 
It is quite certain that this was originally a /usca nest, 
which had been entered by a rufa 9. I took home the @, 
a number of 7ufa 5%, cocoons, and all the fusca 33 we 
could catch. The cocoons have all since hatched and 
have proved to be rufa 5 9. 
Formica sanguinea, Ltr.—This is the robber-ant, our 
only slave-making species. The method adopted by the 
queen of this species is somewhat different to that of 
F. rufa. Having selected her fusca nest, she kills and 
drives away the workers and steals the fusca cocoons. 
These she collects and sits on, and when hatched they 
bring up her brood. I obtained two successful experi- 
ments with sanguinea queens introduced into /usca 
observation nests which I have described in a former 
paper (No. 39). The mixed character of the nest is kept 
up by slave raids undertaken by the sanguinea workers on 
other fusca nests. I was fortunate enough to witness such 
a slave raid in nature at Bewdley last year. This year I 
instituted two mimic slave raids In my sangwinea observa- 
tion nest. I obtained a 2 and a number of 6 6 from a 
sanguinea nest at Woking on April 19th, and placed them 
in a “ Crawley” nest. On June 20th I placed some fusca 
& and a number of cocoons, which I had brought back 
from Braemar, in the last compartment of the nest. The 
sanguineas were in the first compartment. As soon as the 
latter became aware of the presence of the fusca pupae, 
they hurried in, attacked and killed the fusca 3 9, and 
carried off all the cocoons to their own compartment. 
A similar result was obtained with a number of fusca 
cocoons and some @ & I sent up in August from a nest 
in Parkhurst Forest. My friend Dr. Nicholson intro- 
duced them into my sanguinea nest for me. All these 
pupae have hatched, the sanguinea 3 9 helped them out 
of their cocoons, and my nest now contains a large 
number of slaves, which are quite at home with their 
masters. I may mention here that it has been stated 
that the slave-makers only collect the worker pupae of 
Jusca, and never the male and female cocoons. Darwin 
writes: ‘Males and fertile females of the slave species 
(Ff. fusca) are found only in their proper communities, and 
have never been observed in the nests of /. sangwinea.” 
