168 LOCK : STUDIES IN PLANT BREEDING 



deaJl with, and the characters considered were found 

 to behave quite as definitely as in the former case. We may 

 therefore deal here with the two sets of cases simultaneously, 

 and furthermore may begin by taking together all those cases 

 where there was (1) complete dominance, i.e., most cases of 

 starchiness crossed with sugariness,* or (2) where the hetero- 

 zygote, though intermediate, was clearly distinguishable 

 from one of the parental types, i.e., most cases of yellowness 

 crossed with whiteness ; for in such cases no error will be 

 introduced by treating the latter as recessive. 



The summary which immediately follows includes then all the 

 experiments described in this paper, in which, sugar and starch 

 corn having been crossed together, the offspring was crossed 

 with pollen from a sugar variety, together with the correspond- 

 ing cases of (yellow x white) x white; with the exception (1) 

 of those in which the black or blue character was also concerned . 

 and (2) of those few complicated cases where an especially 

 pale yellow character made its appearance, in the later gener- 

 ations, and thus rendered impossible an exact estimation of 

 yellow and white. A small number of plants which bore 

 grains showing both the yellow-white and the starch-sugar 

 characters are counted twice over in the following summary 

 — once for each pair of allelomorphs. 



Throughout this series of cases Mendel's law seemed to be 

 applicable as an approximation. 247 cases were available 

 in which a heterozygote, having been crossed with the corres- 



* Even in the cross starch x sugar, grains intermediate in appoarnm •■ 

 were to bo seen in a smnll number of cases whore certain strains were 

 concerned. Such grains were distinguished by eye into one class 

 or tin- < it In r, and, on rearing their progeny, the classification adopted 

 was almost invariably confirmed. In every case the behaviour of the 

 ing bowed that the doubtful grain belonged in fact to one class 



or the other, and it is highly probable that if chemical tests had been 



applied to these grains the result would have been equally conclusive. 



I he .i iraoter actually used for discrimination is only an incidental 



the fundamental distinction lies in the chemical nature of the 



endoaperm. See Experiments 20 and 54. The error introduced bj 

 includii ii probably inappreciable) 



