MODERN PLANT-BREEDING METHODS 707 



progeny of the hybrid consists of individuals with hermaphro- 

 dite, staminate, and rudimentary lateral florets in the ratio of 

 1:2:1, and further that the individuals with staminate lateral 

 florets break again in the next generation, whilst those with 

 the forms characteristic of the parents breed true from the first. 



Turning now to the colour of the individuals composing the 

 generation raised from the hybrid, they were found to be either 

 black or white with no signs of any intermediate colour. On 

 ascertaining the frequency of these colours there were found to 

 be three black individuals present to each white one, the colour- 

 ing being distributed impartially over the three groups just 

 described. 



This, then, is a case similar to those investigated by Mendel 

 in peas in which one character appeared in its full intensity in 

 the heterozygote whilst its fellow was apparently lost until the 

 succeeding generation. Mendel summed up the behaviour of 

 such characters by terming the one which appeared in the 

 hybrid " dominant," the other, which did not appear until the next 

 generation, " recessive." Black, then, is dominant over white, 

 and it is not practicable to distinguish between the black hetero- 

 zygote and the black parent by colour alone. 



Instead of being able to pick out one pure black to two 

 heterozygotes to one white, we find three blacks to one white. 

 On growing cultures of individual black plants on the average 

 one in three was found to breed true to the black colour, whilst 

 the other two threw off whites in the same proportions as in the 

 previous generation. All the whites, on the contrary, bred true. 

 Two of three blacks were therefore heterozygotes formed by 

 the union of the black-carrying and white-carrying gametes 

 produced by the F. 1. Black and black meeting give a 

 homozygote, black and white or white and black heterozygotes 

 showing the dominant black colour. 



Turning now to the consideration of both pairs of characters 

 together, the importance of these phenomena to the breeder will 

 become evident. Black and white were distributed impartially 

 over the forms with fully fertile, staminate, or rudimentary 

 lateral florets. In other words, the characters of the parents 

 appear in fresh combinations, and in consequence types differing 

 from the parents have arisen. The all-important question to 

 the breeder is the possibility of obtaining these in a stable 

 condition. Such a form as that with staminate lateral florets is, 



