v INTERACTION OF FACTORS 57 



eyes. On self-fertilisation these gave an F 2 generation 

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

 short styled with large eyes, long styled with small eyes, 

 and hornostyled with large eyes. The notable feature of 

 this generation is the appearance of long-styled plants, 

 which, however, occur only in association with the small 

 eye. The proportions in which these four types appeared 

 shows that the presence or absence of but two factors 

 is concerned, and at the same time provides the key to 

 the nature of the hornostyled plants. These are poten- 

 tially long styled, and the position of the anthers is that 

 of normal long-styled plants, but owing to some interac- 

 tion between the factors the style itself is unable to reach 

 its full development unless the factor for the small eye is 

 present. For this reason long-styled plants with the 



Short style \ f Homo style 

 small eye J \ large eye 



Short style 

 small eye 



I 1 ' 1 > 



Short style Short style Long style Homo style 



small eye large eye ("pin") large eye 



(9) (3) (3) (1) 



large eye are always of the homostyle form. What 

 the connecting-link between these apparently unrelated 

 structures may be we cannot yet picture to ourselves, any 

 more than we can picture the relation between flower 



