DISEASES OF CEREAES AND GRASSES 41 



ate together, the former producing" a young plant, 

 the latter a short hypha, the pro-mycelium (see Fig. 

 9, A) and conidia. 



The conidia, on trermination, form a eerm tube 

 capable of penetrating the tissues of the oat plant, 

 but only at this young stage. The plant suffers no 

 apparent effect from the intruder. Hecke, however, 



Fig. 9. — (A) spores of Ustila^o Avencr : (B) a spore germinating in 

 nutritive solution ; notice the septate pro-mycelium (/>) with the oval 

 conidia (c) at the side; (C) spores of Tillctia Tritici : (D) the same 

 germinating, producing a short pro-mycelium with a wisp of long 

 conidia (/) at the end. (Magnified about 300 times. After Brefeld.) 



has shown that the ear may be infected by moisten- 

 ing with water containing smut spores ("Journal 

 B. of Agr.," Feb., 1906, Vol. 12, [)ag(^ 699). 

 The hyph:e grow actively in the growing [)oint of 

 the stem, and when the ear begins to be formed, 

 they break up to form the sooty powder (i.e. the 

 spores), thus revealing the presence of the para- 

 site, 



