ioo Heredity and Eugenics 



with a white having the composition P P r r c c, a ratio of 

 9 purples : 7 whites is obtained in F 2 ; when it is crossed 

 with a white having the composition pprrcc, a ratio of 27 

 purples : 9 reds : 28 whites is obtained in F 2 . 



It is possible that another factorial difference may yet 

 be found which will show this character to be still more 

 complex. Baur, Bateson, Saunders, and Gregory have 

 shown that the sap colors of the flowers of Antirrhinum, of 

 Lathyrus, of Matthiola, and of Primula belong to this type 

 and are yet more complex. But this does not affect our 

 general conception of the inheritance of the colors in the 

 least. 



Sometimes latent characters very similar to this are due 

 to the presence of a second inherited factor which does not 

 allow the first character to develop. This is called latency 

 due to inhibition. Similarly there may be inherited char- 

 acters which help to a more perfect development other 

 independently transmitted characters. This is undoubtedly 

 an important phase of Mendelianism for although we may 

 conceive factors as holding within themselves the poten- 

 tialities of certain characters, they undoubtedly are influ- 

 enced in their development by the development of other 

 inherited characters. One may imagine that factors repre- 

 senting characters may be transmitted but are either not 

 expressed at all or are developed to a limited degree owing 

 to the presence or the absence of other inherited characters 

 that affect this development. 



Perhaps this theoretical conception may be made plain 

 by an example of what has been termed latency of fluctua- 

 tion. In this class are included characters which are poten- 

 tially present in an organism but which may develop to a 

 greater or less extent due to varying influences which sur- 



