72 MYCOLOGY 



of Italy, develops a large edible sclerotium called by the natives 

 pietra fungosa. The sclerotium of Polystictus socer (Fig. 94 A, Teil I, 

 Abt. I**, Die naturUchen Pflanzenfamilien, p. 177), known as 

 Pachyma malacense, is of variable shape, 8 to 10 cm. long, brownish red 

 externally with a white interior. It is found in the Malay Archipelago. 

 These are a few of the true sclerotia which probably includes the 

 "tuckahoe" of the North American Indian, Pachyma cocos. 



Living on limbs, twigs and the leaves of the beech in the deep 

 shade of the forest is found a scale insect {Schizonema imbricator) ,^ 

 which is covered by a woolly coat consisting largely of a waxy secretion 

 from the body. This woolly material is quite abundant and where the 

 insects live in masses together the entire limb, or leaf surface has a 

 downy white appearance. The abdomen of the insect moves con- 

 stantly with a jerky motion and the cottony material is, therefore, 

 constantly agitated. The insects secrete a honey dew so copiously 

 that it runs down to the leaves beneath and to the ground. Upon this 

 honey dew and the dead bodies of the scale insect, a pyrenomycetous 

 fungus, Scorias spongiosa, lives. It grows as a spongy mycelium con- 

 sisting of much-branched, rigid, septate hyphge with the strands glued 

 together by a mucilage. Pyriform perithecia, long-necked spermogonia 

 and pycnidia are formed from the mycelium, which is saprophytic 

 on the products of the insect's body. 



The anther smut of the caryophyllaceous flowers occurs in America 

 and Europe on Cerastium viscosum, Saponaria officinalis and Silene 

 inflaia, and on species of Dianthus, Lychnis, Melandrium, Stellaria, 

 etc. The spores of this smut replace the pollen grains in the anthers 

 of these plants and when the flowers open a violet smut dust is dis- 

 charged from the anthers instead of the pollen. Female flowers of 

 Melandrium attacked by the fungus show a marked morphologic 

 differentiation in the development of mature stamens out of staminal 

 rudiments. These anthers are invaded by the fungus and in them the 

 parasite fructifies. 



The formation of galls is a marked feature of the ecology of fungi. 

 One form of these malformations is seen in the witches' broom (hexen 

 besen) which are due to the attack of a number of species of Exoascus 

 on different forest trees; The branchlets are clustered into broom-like 

 masses with leaves that are somewhat altered in shape and fall earlier 



^Harshberger, J. W.: Joum. of Mycol., 8: 160, October, 1902. 



