390 



BOTANY. 



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

 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 hyphse, 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 

 the remains of the 



tiiim" 0, with old spliacelia.'s ; p, the apex of the dead „ „,„ ^oofi-mrorl nvorc- 

 ovary of rye. B, upper part of ^, in longitudinal sec- nOW-aCStlOyeU OVary 

 tion, showing sphacelia, 8. C, transverse section / A artt] fl Th^io* 1^R\ 

 through the sphacelia more highly magnified ; m, the v^ ciiiu. i>, j. ig. xoaj. 

 mycelnim,surrqnnded wkhthe hyphffi S bearinsco- The COmpaCt, horn- 

 nidia ; p, conidia fallen off ; w, the wall of the oviirv. ^ ' 



J), germinating conidia, forming sporidia, x. A and shaped, and dark-COl- 

 B moderately, C and B highly magnified.— After , , i i ■ ■, 



'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 j^utumi} 



.Fig. 



o'^n^r -too ^G^« 

 198.— CtejA;ep« purpurea. 



A, young eclero- 



