48 

 reported to be attacked only seldom by ergot. 



Because of the wide host range of ergot and considering its 

 eq-ually wide adaptation to many unrelated genera. "a:iieoretically;= there- 

 fore, there is very slight probability for plant breeders to find a great 

 difference among races of rye, barley, and wheat in their susceptibilitji to 

 this fungus. The great difference between rye, barley, and wheat in their 

 degree of infection by ergot (the two latter are very rarely attacked by 

 ergot) is evidently connected with the different modes of flowering of these 

 cereals. Eye usually flowers with opened glumes, wheat and barley with td*. r 

 cjosed glumes, and the closed mode of flowering prevents the two latter 

 from being infected by ergot" (28) . 



Biff en (E3) commmicated the curious fact that there occurred 

 among the P liybrids of Rivet wheat (T. turgidum ) with several varieties 

 of To vulgare some plants vJiich were attacked by ergot, althoixgh the parent 

 forns had never been seen to be attacked by this fungus. Biffin explains 

 this phenomenon as a result of the combiiaation of two Mendelian factors for 

 susceptibility to ergot. These are separated in the parents and in separate 

 forms cannot produce the susceptibility to ergot of wheat, v/hich results 

 when they are combined in the offspring. 



Vavilov (293) gives a different interpretation to theabove 

 fact, for Tfifoich he finds support in a ssSinilar case reported by Rimpau. In 

 1891'Eimpau noticed that in the same hybrid Bivet T. vuleare there ^appears 

 in the F generation some sterile plants. In consideration of this fact 



1. See. the discussion of this subject under "Vr.rieties in relation to 

 ergot infection". 



