V] Antirrhiman and Sweet Peas 99 



The following appearances will then be produced in the 

 flowers by the various combinations. 



AntirrJiinmn 



white 



yello%v 



white 



ivory 



crimson-red 



magenta-red. 



As regards the distribution of the pigments over the 

 parts of the flower, many facts of importance have been 

 discovered (see original papers). Several distinct factors 

 are involved, and by careful analysis Miss Wheldale has 

 been able to show that almost all the heterozygotes can be 

 recognized and distinguished from the corresponding homo- 

 zygotes. The degree to which it has been found possible 

 to effect the genetic analysis of the types in Anth-rhimnn is 

 very remarkable. At first sight the series of forms appears 

 to consist of numberless intergrading tints, but by continued 

 experiment Miss Wheldale has succeeded in disentangling 

 the various o^enetic combinations and showinof the factorial 

 composition of almost all. Even as regards the inheritance 

 of striping an approximate factorial representation has been 

 worked out, though from the fact that striped types may 

 occasionally have self-coloured offspring this part of the 

 analysis must still remain incomplete. 



Needless to say there is as yet no system of colour- 

 reproduction, whether by lithography or photography, which 

 can be applied with accuracy sufficient to represent the 

 various tones of colour, and for the most part the work 

 is unpublished. 



Reversion on Ci^ossing : the Nature of Variation. 



From the facts now before us a clear conception may be 

 formed of the meaning of reversion occurring in conse- 

 quence of a cross. This phenomenon Is due to the meeting 

 together of factors which are complementary to each other, 

 and must be together present in order that the original or 

 reversionary type may reappear. We have seen how In 

 the mouse or rabbit the wild grey type is reproduced when 



7—2 



