GRAMINEOUS CBOPS. 



105 



of rye are so familiar to farmers ttat little need be 

 said of their external characters. They are elongated 

 blackish growths found on spiies of rye (Kg. 40 A) and 

 other cereals as well as on certain mature grasses. A 

 microscopic section through an ergot (Fig. 40 B) shows 

 a compacted mass of irregularly shaped and very thick- 

 walled cells. In what is known as the " early condition," 

 an ergot gives rise to a loosely matted mycelium bearing 



Fig. 41. — GUiviceps purpurea. 



A. A section ttirongli tlie spherical head of the fangiis, showing a number of 



conceptacles (a), x about 11 diam. 



B. A section of a conceptacle, showing a number of asci (b), x 95 diam. 



{Zeiss' B, and 2oc.). 



C. A sporidium. x 270 diam. (Zeiss' B, and loc). 



conidia (Fig. 40 b). This early condition was at one time 

 considered to be a parasite of ergot; but it has been 

 demonstrated that the so-called Oidium abortifaciens is 

 nothing more than an early stage in the life-history of 

 Claviceps purpurea. The oidium-conidia germinate, and 

 reproduce either the oidium-mycelia or the early stage of 

 ergot. When the ergots attain their full size the oidium- 

 mycelia atrophy, and ultimately fall away. Ergots retain 

 their vitality for about two years, and when the surround- 

 ings are favourable they germinate (Fig. 40 C). Each 



