124 CARPOASCI. 



been obtained in luxuriant cultivation with a limited supply of 

 oxygen. 



Capnodium salicinum (Fumago salicina, Cladosporium fumarjo), a common 

 Mildew, forms dark overgrowths on the leaves and branches of 'various shrubs 

 (Poplars, Elms, Willows) and on Hops. The conidia appear in various forms, 

 as on conidiophores, in conidiocarps with large multicellular conidia, and in 

 conidiocarps with small unicellular conidia ; in nutritive solutions yeast-like 

 conidia are also developed. Apiosporium pinophilum produces mildew on the 

 leaves of Abies alba and Picea excelsa? (The conidial-forms were formerly 

 described as " Antennaria pinophila "). 



Order 3. Tuberacese, Truffles. The Fungi belonging to 

 this order are entirely subterranean. The mycelium is filamen- 

 ious, and partly parasitic upon the roots of plants, especially trees, 

 in its neighbourhood ; ^it is then known as Mycorhiza. The f ruit- 

 body is relatively large, in some cases about the size of a hen's 



FIG. 113. Tuber melanosporam : a fruit-body (nat. size), a portion having been re- 

 moved to show the internal structure ; b an ascus with ascospores. 



egg. Internally it is traversed by a number of winding passages 

 (Fig. 113 a), the walls of which are coated with the asci. The asci 

 (&) contain only a small number of spores, and these are set free 

 by the putrefaction of the fruit-body. Conidia are unknown. 



Tuber melanosporum, T. brumale, T. cestivum, and other species are edible. 

 Terfezia leonis and Clioiromyces mceandriformis are also edible. The Truffles 

 are always found in woods and under trees, and disappear when these are de- 

 stroyed. France and Italy produce the best and the largest number of Truffles, 

 which are hunted by specially trained dogs and pigs. 



In Elaphomyces (Stag-Truffle) the fruit-body has a corky external layer, and 

 is inedible. Some of the species are found in this country. E. granulatus is 

 parasitic on the roots of the Fir. 



