290 



BOTANY. 



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

 fected one is 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 hyphffi, which 

 bear a few small 

 spores (xporidia, D, 

 Fig. 198, a;), which 

 th e mselves 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 



the remains of the 



lir . w d 00 frnvorl ,\\-r\- 

 nOW-dCStrOV Cd ()\ ill \ 



tion, showing gpliarelia, s. 0. transverse section / I anr\ 7? V\cr 1 Q8"l 



t hrongh the xphnrelia more highly magnified ; m, the (- 1 ana ^' *'? *W- 



niyoefjnm, pnrroiindi'd with the hyphw b, hearing co- The COmililCt lioril- 



i.idia ; p. conidiu fall, n off : w. the vail of the ovliry. ' )I"PltL, L 



/>, germinating conidia, forming sporidia, a:. A and shaped, and (lark-COl- 

 B moderately, 6' and D highly magnifled.-After. J , , 



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 



Fig. 198. Clai-iceps jnirpurea. A, young eclero- 

 tium, o, with did sphacelia, ; /. the apex of the dead 

 ovary of rye. S, upper part of A. in longitudinal sec 



