206 



GENETICS IN RELATION TO AGRICULTURE 



linked character. As it occurs in the wild, the currant moth is usually 

 of the typical form which is characterized by dark markings on the wings 

 which although highly variable are of characteristic shape and arranged 

 in a definite pattern. This is the form styled grossulariata. Occasionally 

 in nature, however, a female is discovered which is much lighter than 



R 



F, 



F, 



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Fio. 93. Diagram illustrating the inheritance of lacticolor type in Abraxas. A lacticolor 

 female mated to a grossulariata male. (Adapted from Morgan.') 



the type on account of a reduction both in number and size of the black 

 markings of the wings. This is the form styled lacticolor. It is of in- 

 terest to note that according to Doncaster, save in one doubtful case, 

 only females of the lacticolor type have been discovered in nature. 



The inheritance of lacticolor type is illustrated diagrammatically in 

 Figs. 93 and 94. In these diagrams the TF-chromosome is represented 



