290 



BOTANY. 



A 



so on. The contact of an infected head of rye with an unin- 

 fected ouo$s sufficient to communicate the fungus to the 

 latter, and doubtless the conidia are also freely carried by the 

 winds, and, to a certain extent, by insects. It appears that, 



in some cases at least, 

 the germinating co- 

 nidia produce, first, 

 short hyphae, which 

 bear a few small 

 spores (sporidia, D, 

 Fig. 198, x), which 

 themselves germi- 

 nate, and then pro- 

 duce the sphacelia ; it 

 is doubtful, however, 

 whether this always 

 takes place. 



384. After the 

 conidial stage, the 

 mycelium at the base 

 of the ovary becomes 

 greatly increased, and 

 assumes a hard and 

 compact form ; it 

 grows with a consider- 

 able rapidity, and car- 

 ries up on its summit 

 the old sphacelia and 



Fig. 198. Clavlceps pnrpurea. A, young sclero- the remains of the 

 tium, c, with old sphacelia, s ; p, the apex of the dead dpefrnvprl nvarv 



ovary of rye. B, upper part of A, in longitudinal sec- nOW-dCSt! OyCC OVary 

 tion, showing epliacelia, s. C, transverse section / A Q -nA ~R TTirr 1 Q8\ 

 through the sphacelia more highly magnified ; m, the \ A dllu -> rl &' **">/ 

 mycelium, surrounded with the hyphtu b, bearing co- Thp pnmnnp(- hnrn- 

 nidia ; p. conidia fallen off ; w, the wall of the ovary. J >m.p<itl, J 



D, germinating conidia, forming sporidia x. 4 and shaped, and dark-COl- 

 B moderately, C and D highly magnified. After 



sachs. ored body which re- 



sults is called the sclerotium ; that which is produced upon 

 rye is from one to three centimetres long (.4 to 1.2 in.) and 

 from two to six millimetres in diameter (.08 to .25 in.) ; on 

 other grasses it is usually of less size. The sclerotium occu- 

 pies the position of the displaced ovary, and in the autumn 



