898 JOURNAL OF THE BOYAL HORTICULTURAL SOCIETY. 



genera. As a result of Darwin's great work, the term species " hag 

 naturally become somewhat less definite as a unit, but it is a convenient 

 term nevertheless, and it remains to be seen whether the American defini- 

 tion of "hybrid" will come into general use. 



Breeding for Special and Neiu Uses. 



Prof. Hays throws out some interesting suggestions for future 

 hybridists and breeders — e.g. the breeding of increased nitrogen com- 

 pounds into field crops, so as to make them mora valuable as food. He 

 also refers to Mr. Swingle's suggestion that the nitrogen-gathering 

 bacteria associated with the nodules on clover roots could be bred so as 

 to be more actively useful, in the same way that brewers have success- 

 fully bred special varieties of the yeast plant for making beers of different 

 qualities. 



Prof. Hays says : — " There is no reason why the nitrogen content of a 

 variety cannot be increased as well as the sugar content, flavour, hardi- 

 ness, height, or any other naeasurable characteristic." 



Prof. Hays proceeds to give some practical illustrations of the methods 

 of plant breeding at the Minnesota Station, those on the manipulation 

 and pollination of wheat flowers being most interesting. Prior to cross- 

 ing, the Wheat florets have of course to be emasculated, generally from 

 one to two days before the flowers open ; when the flowers open, the- 

 foreign pollen has to be introduced within the space of a few minutes, 

 as they are soon over, sl^owing the necessity of careful observation and 

 manipulation. 



Prof. Hays gives an interesting photograph (p. 56, pi. vi., fig. 1), 

 showing how "hybridising" Wheats causes variation. Two pure-bred 

 varieties of Wheat, i.e. ' Fife ' and ' Blue Stem,' are crossed and pro- 

 duce a rather inferior-looking ear unlike either of the parents. The 

 progeny of this in the second generation, self-fertilised, produced, out of 

 100 plants, thirteen totally distinct Wheats, including bearded and awn- 

 less, long and short, loose and compact ears, and, what is really more 

 remarkable, several of them are much like the different so-called 

 " species " of Wheat. Whether this is proof that all the domesticated 

 Wheats originated from a single species, or whether they have been pro- 

 duced by hybridisation from several species, is difticult to say. One thing 

 is clear, however, and that is that there is a blood relationship between 

 the different classes of Wheat. As Prof. Hays says, " It is a remarkable 

 illustration of the intricate relationships existing in nature even among 

 plants apparently exclusively self -fertilised." Prof. Hays gives a good 

 illustration of how quickly a variety can be fixed after " hybridisation." 



" In 1893, from a floret of ' Blue Stem ' Wheat pollinated from a ' Fife 

 plant, there resulted a seed which in 1894 developed into a plant. . . . 

 In 1895 a ' centgener ' of plants was grown from the 1894 mother plant. 

 Of these 30 per cent, had smooth chaft', resembling the ' Fife ' parent, and 

 70 per cent, had hairy, velvety chaff, resembling the ' Blue Stem ' parent. 

 In the succeeding years smooth-chaffed plants were chosen for mother 

 plants from one stock selected for the development of a smooth-chaffed 

 variety, and plants with velvety chaff were chosen as mother plants from 

 another -stock selected for the development of a hairy-chaffed variety. . . . 



