1130 EXPERIMENT STATION liECORD. 



From 30 to 40 plants wcro rnis(vl from iiidiv idnuls of the F. 2 sfiioration. 

 these being selected for (he iiiosi p.iri Im- ircessivc (li;iff and color characters. 

 The Ki'i^iii characters of iiareiil and pro^'eiiy were as follows: The F. 2 ^iMiera- 

 tion jtlants of ItoiiKh Chaff crossed with Fife, which were used in the test, repre- 

 sented 50 strong and 12 weak plants, and the types of the F. 8 generation 

 showed 10 strong, 34 mixed, and 12 weak plants. In the case of the hybrid 

 between Lammas and Ked Fife the F. 2 generation i)lants sown represented ;"() 

 strong, 20 mixed, and 10 weak individuals, while the tyi)es of the F. 3 plants 

 showed 50 strong, 3 strong and 17 mixed as corresponding to the 20 mixed in 

 the F. 2 plants, and 10 weak individuals. It is pointed out that in the tirst 

 case strength is dominant to lack of strength and that the heterozygotes are 

 indistinguishable from the dominant honiozygotes, but that in the second case 

 the domination is not so shari)ly marked and the heterozygous individuals can 

 be distinguished with a certain degree of accuracy. These examples were 

 typical of some 30 others, but in most of them it was not considered necessary 

 to determine whether the recessive lack of strength was pure from the moment 

 of its appearance in the F. 2 generation. Forty of 66 strong cultures proved 

 homozygous in all respects. The grain of the F. 3 generation was iilanted and 

 the result demonstrated the value of Mendeliau methods, for in this F. 4 genera- 

 tion the types appeared perfectly fixed. 



The milling of these grains showed that they were strong wheats, and this 

 character was so prominent that the miller without knowing the origin of the 

 grain he was grinding noted that it ground like Manitoban wheat. Later, baking 

 tests also confirmed the conclusion that strength and lack of strength segregate 

 from one another in the F. 2 generation in the same manner as the morpho- 

 logical characters already examined. 



In another experiment of this kind, a cross between Polish wheat {Triticum 

 poloiiicion) and Rivet wheat (T. tingidum) was studied. The grain of the 

 Polish wheat is brittle, translucent, and white in color, and has an average 

 nitrogen content of 2.2 per cent, while the Rivet wheat is a typical starchy 

 red wheat with a soft, mellow endosperm and an average nitrogen content of 

 about 1.6 per cent. In the F. 1 generation the grain was uniformly brittle, 

 translucent, and red. In the following generation the expected segregation into 

 red and white, translucent and starchy grains occurred, but the mode was not 

 as simple as in certain of the crosses referred to above. When the endosi)erm 

 characters were taken into consideration it was found that many plants pro- 

 duced grain which could not satisfactorily be placed in either the starchy or the 

 translucent class. The results of a further examination showed that the dis- 

 tribution of the nitrogen content is not affected by the shape of the glumes. It is 

 stated that the failure to give sharp segregation into two or more groups in the 

 F. 2 generation is not uncommon in crosses between cereals. In the F. 3 gen- 

 eration it was shown that all plants selected on the basis of short or long glume 

 character bred true to these characters, and that w^hen they were chosen from 

 the intermediate series they proved heterozygous. The author points out that 

 an analysis of the F. 3 generation is required to unravel the mode of segrega- 

 tion, when it will be found that the heterozygotes can be at once distinguished 

 from the homozygotes and that they occur in the ordinary Mendellan pro- 

 portions. 



The analysis of the F. 2 generation showed that the grains with a translucent 

 endosperm were high, and those with a mellow, starchy endosperm low in nitro- 

 gen. Grains flecked with starchy patches generally showed an intermediate 

 nitrogen content, but the percentages varied w'idely. A slightly flecked sample, 

 for instance, did not always show a higher content than one in which the grains 

 were starchy. The plants producing translucent grain were considered to be 



