THE FUNGI: ASCOMYCETES AND BASIDIOMYCETES 281 



Fig. 273. — Schizosaccharomyces octosporus. A, Vegetative cell. B and C, Division of 

 vegetative cell. D to F, Conjugation and formation of fusion nucleus. G to L, Develop- 

 ment of ascus and formation of eight ascospores. {After Guilliermond .) 



/ Hypocreales 



The Hypocreales are Ascomycetes in which the asci are arranged in a 

 perithecium which opens at the top by an ostiole. This perithecium is flask- 

 shaped, and is either free or sunk in a stroma formed from the tissues of the 

 Fungus. The asci usually produce eight ascospores which are generally 

 hyaline, elliptical or filiform in shape, and may be composed of more than 

 one cell. The stroma, and the perithecia when free, are often brightly 

 coloured, red, yellow or purple being common shades. 



The group includes a number of interesting species, some of which are 

 of economic importance. Species of the genus Nectria form bright red 

 stromata on the surface of wood, pushing up and cracking the bark in the 

 process. On account of their colour and appearance these Fungi are called 

 the Coral Spots, and at least one species causes a canker disease of fruit trees. 

 Other members of the group live as parasites, mainly of tropical insects, the 

 bodies of which become filled with the fungal mycelium until the creature 

 is killed. The peculiar appearance produced as a result of the growth of 

 the Fungus out of the body of an insect gave rise in earlier times to a belief 

 that they possessed medicinal and magical value. Cordyceps sinensis on 

 caterpillars, for example, was a celebrated drug in the Chinese pharmacopoeia. 



We shall consider one example of this order, Claviceps purpurea, which 

 causes a disease known as Ergot of Rye. The Fungus contains a powerful 

 muscular stimulant and is still used for medicinal purposes. 



Claviceps purpurea (Ergot of Rye) 



The Fungus, though characteristic of Rye, also attacks other species of 

 grasses (Fig. 274), including Wheat and Oats. There are several biologic 

 races : e.g., that growing on species of Lolium being incapable of infecting 

 Rye and other cereals. 

 10 A 



