FORMICA. 331 



They were like a sponge, and when squeezed water ran out of 

 them ; only the chamber in the upper part of the dome and the 

 entrances to the galleries being dry. 



He often noticed grass stems growing through the nest, which 

 at first he thought acted as pillars, in the same way as D. nigra 

 uses grass stems to support its architecture, but he subsequently 

 found that a number of black aphides were seated on these grass 

 stems and sucking the juices from them ; it is probable that the 

 ants had built the nest round the stems on this account. In the 

 hillocks he found cocoons, but rarely larvae, though in the hot 

 weather most of the colony came up into them. 



He says that not all nests are covered by a hillock, but that in 

 such cases he never found the winged sexes nor brood in them. The 

 colonies consisted of from fifty to one thousand individuals, but 

 usually of six to eight hundred. 



As he points out, the shining greasy (" fettige ") chitinous 

 covering of these ants enables them to live in such wet places, 

 but they always have wet feet, which can be proved by allowing 

 them to walk over a pane of glass, when the wet marks made by 

 their feet can be seen. 



He found the winged females and males in the nests in July and 

 August, but never in September, t'he females always being more 

 abundant ; on the other hand as we have seen Crawley and I only 

 obtained males in 1912, and in 1914 I found this sex to be far more 

 abundant than the females. The worker pupae were usually in 

 cocoons, but in September and later they were often naked, and 

 he states he does not know how the colonies are founded. 



On September 9th, 1912, he fixed up a small colony in a Lubbock 

 nest, but the ants never worked in the earth, though they built a 

 small wall with some sphagnum which had been introduced into 

 the nest. Some larvae and cocoons of F. fusca were given to them, 

 when they opened the latter and devoured the pupae, but accepted 

 the former and covered them with bits of earth when ready to 

 pupate. 



He calls attention to the fact that Sahlberg 10 found a mixed 

 colony of this species and F. sanguined in Finland, which was 

 living in a sphagnum nest. 



Wasmann, in commenting on this, suggests that either a san- 

 guinea female had been accepted into a colony of picea after her 

 marriage flight, or she had stolen some of their cocoons 37 . 



The latter author also considers that the picea workers covering 

 the larvae with bits of earth is a case of atavism, as this ant in 

 normal conditions would not possess earth for this purpose 37 I 

 have found however that ants in plaster nests where there is no 

 earth present will use bits of plaster, cotton-wool, or anything they 

 can get hold of for this purpose and he points out that the white 

 colour of these nests is caused by the fact that the sphagnum leaves 



