Manchester Memoirs, Vo/. Ivi. (igii-12). 11 



experiments made by Prof. Biffen with various varieties 

 of wheats. The strains of British wheats which are 

 remarkable for their heavy crops are unfortunately not of 

 such value as the hard, flinty varieties of the Canada and 

 America, as they contain less gluten, the substance which 

 gives to the flour good baking properties ; moreover many 

 of the British wheats have been very susceptible to the 

 fungus producing the rust of wheat. Biffen's experiments 

 lead him to believe that richness in gluten and immunity 

 (i.e., comparative immunity) to disease are unit characters 

 giving simple Mendelian ratios, and he has consequently 

 been able to unite these desirable qualities with heavy 

 cropping capacity in wheats suitable for the British 

 climate. 



Similar useful investigations have been carried on by 

 Nilsson-Ehle,the head of the experimental farm in Sweden, 

 and confirm to some extent the conclusions of Biffen. 

 But the Swedish investigator finds"- that though strains of 

 different degrees of susceptibility or immunity to disease 

 (rust of wheat) segregate out from the second and subse- 

 quent hybrid generations of wheats, the fluctuation in 

 respect to this character is often greater than the degree 

 of immunity of the two parents, i.e., some of the offspring 

 in (/2) and (/3) generations are more susceptible to disease 

 than the more susceptible parent, and some of the offspring 

 are more resistant than the resistant one. The offspring, 

 too, of equally resistant forms do not show equal resistance, 

 but considerable variation in this respect. He concludes, 

 therefore, that susceptibility or immunity is not a unit 

 character, but is dependent on several factors, which may 

 combine in various ways and thus determine the appear- 

 ance of considerable fluctuations in this respect. 



- H. Nilsson-Ehle. Kreuzungsuntersuchungen an Hafer und ^yeizen. 

 Lund Universitets ArskriUer. Bd. 7, No. 6, 191 1. 



