1 9 1 1 - 1 9 1 2 . ] Notes on Parasitic A scornycetes. — //, 43 3 



be noticed in the present paper as truly parasitic during the 

 whole course of their life-history. Leaving out of account 

 certain rare and little-known forms, as well as various species 

 which are parasitic on lichens, algae, &c., 15 genera (viz., 

 Claviceps, Cordyceps, Epichloe, HypomyceSy Nectria, Polystigmaj 

 Phyllachora, Pothidella, Botryosphceria, Cucurhitaria, Gihhe^rc, 

 Gnomoniella, Venturia, Stigmatea, and Sphcerella) may be 

 briefly noticed as coming within the scope of our review. 



The genus Claviceps is represented by C. jpiirpurea (Fr.) 

 TuL, which attacks various grasses when at their flowering 

 stage. Over the ovary of the grass is formed a whitish 

 covering of mycelial tissue, on the surface of which are de- 

 veloped conidiophores bearing very minute conidia. In this 

 condition the fungus has been described as Sphacelia segetiim 

 Lev. Along with the conidia is exuded a sweet liquid which 

 attracts insects, and these become the medium whereby the 

 parasite is conveyed from flower to flower. As the conidia 

 germinate at once, the infection often spreads very rapidly. 

 After the dispersal of the conidia the whitish mass of mycelial 

 tissue increases in size, and becomes densely compacted into a 

 hard sclerotium of a purplish- black colour and elongated horn- 

 like shape. This form of sclerotium is commonly known as 

 an " ergot." It falls to the ground, where it remains quiescent 

 till the following spring. It then gives rise to one or more 

 stromata. Each of these consists of a short stalk, surmounted 

 by a rounded head in which are immersed the numerous 

 perithecia. The asci contain spores which are narrowly 

 filiform in shape, and are probably dispersed by the wind. 

 A less common species {C. nigricans Tul.) occurs on the 

 flowers of the marsh spike-rush (Pleocharis palustris), where 

 it produces black ergots similar in form to those of 

 (7. purpurea. 



Of the genus Cordyce-ps, the best-known species is C. militaris 

 (L.) Link, which is common in moss-grown pastures in many 

 districts. It attacks living larvae of moths, and kills them 

 when they have passed into the pupa state. The conidial 

 condition (known as Isaria farinosa Fr.) is developed from 

 the dead pupa when it occurs in moist shady banks in woods. 

 It consists of a cluster of white stems which are thickened at 

 their extremity, and are copiously powdered over with the 



VOL. VI. 2 H 



