m l Heterosiylism 69 



that Primula Sinensis, which is preferred by fanciers in the 

 pin form, was easily bred true to that type, and is always so 

 maintained in good strains. For our experiments it was 

 with considerable difficulty that we procured any thrum 

 plants. On the other hand it was decided long ago that 

 the Auricula and the Polyanthus for exhibition purposes 

 must always be thrums, but though thrums have thus been 

 largely selected for breeding, pin-eyed plants are continu- 

 ally reproduced, as must be expected, for the thrum is a 

 dominant, and therefore liable to contain the recessive type. 

 The facts about to be described relate to an experiment 

 made with a peculiar race of P. Sinensis grown by Messrs 



Fig. 14. Some of the types of flowers in F^ from the cross short-style 

 (thrum) ; small eye x homostyle ; large eye. 



A. The long-styled flower : with small eye. 



B. The homostyled : large eye. 



C. The short-styled : small eye. 



D. The short- styled : large eye. 



In the two upper flowers the corolla is of the " star " type. D is 

 the ordinary, imbricated type of Sinensis. C is more or less inter- 

 mediate in corolla-shape. This shape is the usual heterozygote formed 

 between star type and Sinensis type. The corolla -shapes are of course 

 quite independent of the style and " eye " characters. 



