258 LOCK : 



the development of the purple colour which may appear when 

 two white-flowered sweet peas are crossed together. 



The principal conclusions arrived at by East and Hayes are 

 expressed in the lij^otheses here enumerated. 



A cob from a cross-bred plant from either purple x white 

 or white X purple may bear F2 grains in the proportion of 

 either 3 P : 1 W or 9 P : 7 W on self-fertilization. 



These ratios are explained bj^^ supposing that the purple 

 colouration, as in the case of the flowers of the sweet pea, 

 (lepend.s upon the simultaneous presence of two separate factors 

 P and C. If one of these factors is present in both parents 

 and the other in the purple parent only, the result is a simple 

 Mendclian ratio in r2. If both factors are present in the 

 purple parent and neither in the non-purple parent, a ratio of 9 : 

 7 is obtained in F2 in accordance with the well known formula. 



In certain families the coloured grains could be differentiated 

 into purples anrl reds, the former being three times as numerous 

 as the latter in the simplest cases. In order to explain these cases 

 a .separate factor R is hypothecated which is hypostatic to P. 



In certain families particoloured or very light purples made 

 their appearance in such numbers as to suggest that their 

 gametic fornmla is correctly represented by the expression 

 Pc. It is therefore supposed that in these cases the appear- 

 ance of the purple colour is not. entirely .suppressed by the 

 absence of the factor C. 



In a final experiment the cross between purple and non- 

 jinrple resulted in a certain proportion of white grains. This 

 plicnomenon is explained ))y the presence of an inhil)iting 

 fa<-t<)r J. in the presence of which the red or purple pigment 

 failh to (leveloj). 



It should be noticed that no case has so far been ob.served 

 ill maize of the curious relation between allelomorphs, wiiich 

 is spoken of a« redui)licati(m l)y Bateson and Punnett in their 

 latest j)ul)lication u])()n the subject.* 



AH the above postulates have their analogies in the work of 

 authors who have dealt with other groups of animals and 

 plants. All were further confirmed by East and Hayes from 

 thu study of further generations of the hybrids. It is therefore 



• Journal of Qenetics, Vol. T.. No. 4, IHl ? 



