DONISTHORPEA. 193 



which the ants chew up ; but that of the salivary glands seems 

 more likely for this purpose. 



These nests are often very large, having the appearance of a 

 huge sponge, and consist of a number of irregular cells separated 

 from each other by thin carton walls, which are rather brittle and 

 generally black in colour, but sometimes light brown, according to 

 the amount and the colour of the earth used in their construction 

 the carton of a nest I found in the Isle of Wight was of a light 

 reddish brown colour. The carton contains a quantity of a fungus 

 which was named Septosporium myrmecophilum by Fresenius, 

 Saccardo describes it as Macrosporium myrmecophilum, but con- 

 sidered it might be identical with Cladotrichum, and Lagerheim 

 came to the conclusion that it was really a Cladotrichum, and 

 called it C. myrmecophilum' 11 . (I supplied Dr. Jessie Baylis 

 Elliott of the Birmingham University with various samples of 

 D. fuliginosa carton, and she has proved, by making cultures, etc., 

 that the fungus it contains is a Cladosporium, and so should be 

 called Cladosporium myrmecophilum 62 .) The " raison d'etre" of 

 this fungus is probably twofold, the hyphae may act as food for 

 the ants and their brood it forms a delicate bluish mould on the 

 walls of the cells and under the microscope it may be seen to 

 have been bitten off by the ants and the mycelium helps to 

 strengthen the walls of the nest. The ants most probably culti- 

 vate this fungus intentionally, as no other species of fungus is 

 found in these nests, but it would not alone supply sufficient food 

 for the teeming myriads that go to form the population of a large 

 colony. 



Dr. Sharp says this species lives in decayed wood 38 , but though 

 its nests are generally built in hollow trees, old tree stumps, and 

 posts, they frequently occur in the ground, at the roots of, but also 

 away from, trees, and even in houses and cellars, etc. 



On September 9th, 1913, I dug up a nest at Oxshott which was 

 thirteen inches long, nine and a half inches high, and eight and a 

 half inches broad, and was situated under the roots of a large 

 Scots fir some three feet below the surface of the ground. The 

 earth surrounding the nest was of a soft sandy nature, but just 

 below it the ants had excavated small chambers in the ground, 

 and the soil round these was almost as hard as stone. 



Smith records it as nesting in a sand-bank at Southend 11 ; near 

 Coomb Martin, in the mud walls by the roadside 16 ; near Ilfracombe 

 he observed it inhabiting fissures in the rocks 16 ; Farren- White 33 

 speaks of it as a miner at Clevedon, and White Notley ; Perkins 28 

 found an enormous colony in a sandy bank at Stoke Fleming in 

 1891 ; and Rothney 36 mentions its occurrence in an earth bank on 

 the Headland at Newquay in 1899. 



In August, 1914, I observed a number of D. fuliginosa workers 

 attending large black Aphidae on some young birch trees on 



