152 PYRENOMYCETES [ CH . 



them to other flowers, where they at once germinate, and further infections 

 are produced. On the completion of the conidial stage the sclerotia assume 

 a firmer texture, and become dark purple or bluish black in colour. If they 

 fall to the ground or are sown with the seed they give rise next spring to 

 numerous stromata with violet stalks and reddish yellow heads. According 

 to Fisch, the perithecia originate from two or three hyphal cells, which 

 become filled with strongly refractive protoplasm and divide in all directions 

 to form a roundish mass of cells distinguished from those of the rest of the 

 stroma by their size and contents. As in Cordyceps, there is no trace of 

 sexual organs. The perithecia are immersed in the stroma, and the asci 

 produce filiform but continuous spores. 



The sclerotium is well supplied with reserve materials and contains certain 

 poisonous substances including ergotic acid, a narcotic which diminishes 

 reflex excitability ; sphacelic acid, the main cause of ergot poisoning, it 

 gives rise to gangrene, and large doses produce tetanus of the uterus and 

 cramp ; cornutin, an alkaloid causing contraction of the uterus. 



Thus the ergot sclerotia, if eaten with the grass by cattle, or included in the 

 grain used for bread-making, are responsible for serious disease. When grain 

 was less carefully purified than at present the inhabitants of whole districts 

 sometimes became afflicted with gangrene, and the occurrence of the sclerotia 

 in pastures is liable, owing to the presence of cornutin, to cause abortion in 

 sheep or cows, so that many local traditions as to the prevalence of abortion 

 in certain farms, or in certain byres, are probably traceable to this cause. 



Cornutin is of medicinal value, and the sclerotia are collected for this 

 purpose. 



HVPOCREACEAE : BIBLIOGRAPHY 



1843 BERKELEY, M. J. On some Entomogenous Sphaeriae. London Journal of Botany, 

 ii, p. 205. 



1882 Fisch, C. Beitrage zur Entwickelungsgeschichte einiger Ascomyceten. Bot. Zeit. 

 xl, p. 850. 



1883 Frank, E. Ueber einige neue oder wenige bekannte Pflanzen Krankheiten. Ber. 

 der deutsch. bot. Ges. i, p. 761. 



1895 Massee, G. A Revision of the Genus Cordyceps. Ann. Bot. ii, p. 207. 



1901 Lewtox-Braix, L. Cordyceps ophioglossoides. Ann. Bot. xv, p. 522. 



1905 ATKINSON, G. F. Life-history of Hypocrea alutacea. Bot. Gazette, xl, p. 401. 



1907 DANGEARD, I'. A. Recherches sur le developpement du perithece chez les Ascomy- 



cetes. Le Botaniste, x, p. 352. 

 1912 Blackman, V. H. and Welsfokd, E. J. The Development of the Perithecium of 



Polystigma rubrum. Ann. Bot. xxvi, p. 761. 

 1114 NlENBERG, W. Zur Entwickelungsgeschichte von Polystigma rubra. Zeitschr. fur 



Bot. vi, p. 369. 



DOTHIDEALES 

 The Dothideales constitute a small group of some four hundred species, 

 included in twenty-four genera, forming a single family, the Dothideaceae. 

 They are parasites or saprophytes on the leaves and stems of higher plants, 



