52 



MENDELISM 



CHAP. 



large. Besides the normal long and short styled 

 forms, there occurs a third form, which has been 

 termed homostyle. In this form the anthers are 

 placed low down in the corolla tube as they are in 

 the long-styled form, but the style remains short 

 instead of reaching up to the corolla opening (Fig. 

 9, C). In the course of their experiments Bateson 



Fjg. 10. 



Two primula flowers showing the extent of the ^m?i\\ and of the large eye. 



and Gregory crossed a large-eyed homostyle plant 

 with a small-eyed thrum ( = short style). The F^ 

 plants were all short styled with small eyes. On 

 self- fertilisation these gave an F., generation consist- 

 ing of four types, viz. short styled with small eyes, 

 short styled with large eyes, /on^ styled with small 

 eyes,, and homostyled with large eyes. The notable 

 feature of this generation is the appearance of long- 

 styled plants, which, however, occur only in associa- 

 tion with the small eye. The proportions in which 

 these four types appeared show that the presence 

 or absence of but two factors is concerned, and at 



