FORMICA. 291 



D. Sharp says sanguined very frequently lives without slaves 44 , 

 but this is hardly the fact, at any rate in Europe. Forel mentions 

 that in Switzerland he has seen a few colonies of sanguined without 

 slaves 24 , and Wasmann says that in Holland such slaveless colonies 

 are very rare 35 . 



Forel, when recently describing a very large community of 

 sanguinea without slaves, records that only three or four times in his 

 life has he ever before found sanguinea without slaves. At the 

 Chalet Boverat below Lausanne in a large meadow he discovered 

 forty sanguinea nests, two to five metres distant from each other, 

 over a length of over one hundred and fifty metres, all connected 

 by chains of ants, and not a single slave occurred in any of them. 

 He thinks it probable that the sanguinea had exterminated all the 

 fusca species in the neighbourhood, as he was unable to find a single 

 nest anywhere near 74 . 



I have never found a sanguined nest in Britain which did not 

 contain slaves, and the suggestion that our species is less aided by 

 its slaves than those in Switzerland appears to me to be very 

 doubtful. 



Wheeler points out that the normal slaves of F. sanguinea are 

 members of the F. fusca group, namely, fusca, glebaria, rubescens, 

 gagates, rufibarbis, and cinerea, but it occasionally enslaves members 

 of the rufd group (rufd, pratensis, and their varieties). He says 

 there can be no doubt that the typical fusca is the form most fre- 

 quently enslaved in Northern Europe and at high elevations in the 

 Alps, but in the valleys of Switzerland the varieties glebaria and 

 rubescens and F. cinerea are the commonest slaves 69 . 



Wasmann found that in Holland fusca was the most common 

 slave-species 35 , but that in Luxemburg rufibarbis was more generally 

 used 62 . 



Two fusca forms may be present in one sanguinea nest, or even 

 fusca and rufa forms together. 



On July 27th, 1875, Forel observed a rufa-like nest on the side 

 of a road near Laegern which on examination proved to contain 

 both sanguined and rufd workers, the latter being a little more 

 numerous than the former, and generally small in size, and no fused 

 workers were present 26 . Wasmann on the other hand found a 

 sanguinea colony at Exaeten in which ten per cent of the slaves were 

 rufa, and five per cent fusca 35 . 



In the summer of 1886 Forel discovered a sanguinea-pratensis 

 colony at Fisibach in which the former were of large size and more 

 numerous than the latter, which were small in stature 32 . Wasmann 

 has also observed sanguinea colonies which contained only pratensis 

 as slaves, as well as colonies with both fusca and pratensis as 

 slaves ; but a sanguinea-fusca-pratensis colony described by Riisch- 

 kamp is a rather more complicated affair. In April, 1911, he knew 

 of a normal sanguinea-fusca colony, which was partly dug up May, 



