I3h' LOCK : STUDIES TN PLANT BREEDING 



actually carried out. But in spite of careful attention it was 

 difficult to ensure the complete exclusion of foreign pollen 

 and. in the absence of other information as to the behaviour 

 of the blue character, such cases as the following seemed to 

 show that tlit- method employed was quite inadequate. 



Expt. 55. -The stigmas of a plant arising from a blue grain 

 of No. 1 were covered with a paper bag and fertilized with 

 pollen from the male flowers of the same plant. The cob 

 yielded 172 blue grains, 99 yellow, and 36 white. Among 

 non-blue grains there were thus 73 per cent, of yellow and 

 27 per cent, of white grains, a proportion which approaches 

 the Mendelian ratio 3:1. But the ratio of blue to non-blue 

 grains was 56 : 44. 



Expt. 56. — A plant from a blue grain of No. 5 yielded on self- 

 pollination 268 blue grains and 182 non-blue, or 59-5 : 405 



Subsequent observations showed that the error in these 

 cases was probably small or even non-existent, but at the time 

 no explanation was forthcoming.* For this reason, and also 

 because the cobs so produced yielded as a rule only a small 

 number of scattered grains, the remaining crosses made at this 

 ttme were not noted very fully, and in subsequent generations a 

 different method was adopted. This was the same as was used 

 in all the later generations from the definite crosses previously 

 described, namely, fertilization in mass of the emasculated 

 oroes-bred plants by the pollen of a white strain. 



A. — Sinole Pairs of Characters. 



1. YELLOW AND NON-YELLOW (WHITE). 

 White grains (V) from cob No. I produced plants which, 

 Oil pollination principally among themselves, yielded !>0 per 

 cent, or more of white grains ; they also showed as a rule less 

 than 10 per oen< oi yellow grains and lass than 5 per cent, of 

 Uae grains ( Fi ). These yellow and blue grains u i re d< >ubt less 

 sof "xenia produced by thepoUent of surrounding plants 



The definite . I. ■-.- -i-i J >. c i . which throw light on those 



aomene, wn no! parried oui until <• later date 



