196 



ASCOMYCETES. 



other characters coincide ; this seems to be all the more justifiable since 

 one finds on the same species asci with spores made up of one, two, or 

 four cells. 



Trichosphaeria parasitica Hartig.^ (Britain and U.S. 

 America.) Everywhere in young naturally regenerated woods 

 of silver fir, especially in damp places or where the plants 

 are crowded, one finds partially browned needles hanging 

 loosely from the twigs, held only by a fine white mycelium 

 (Fig. 87). In addition to this, one finds in spring young 

 twigs completely enveloped in mycelium, with all their 



Fk;. ST. — Trichosphaeria parasitica on Silver Fir. The withered and dead 

 needles hang loosely downwards, attached to the twig only by a white mycelium, 

 (v. Tubeuf phot.) 



needles killed, so that the twig itself soon dies. The white 

 mycelium grows especially on the under side of the shoot, 

 and on the lower epidermis of the horizontal needles. A 

 pseudoparenchyma, consisting of layers of mycelium, is there 

 laid down, the lowest layer of hyphae sending short cone- 

 shaped haustoria into the walls of the epidermal cells (Fig. 88). 

 Inside the needles, occupying the intercellular spaces, there 

 are numerous branches of septate hyphae, which kill the cells 

 of the leaf. The perithecia occur here and there on the 

 mycelial coating outside the leaf; they are spherical and 

 blackish, with radiating hairs. They contain paraphyses and 



^ R. Haitig, "Ein neuer Parasit d. Weisstanne. " Alhri. Fornt.-u. Jatjd- 

 ZtitwKj, Jan., 1884. 



