V INTERACTION OF FACTORS 53 



the same time provides the key to the nature of the 

 homostyled plants. These are potentially long styled, 

 and the position of the anthers is that of normal long- 

 styled plants, but owing to some interaction 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 



Short style \ „ / Homo style 

 small eye / \ large eye 



Short style 

 small eye 



, , I , , 



Short style Short style Long style Homo style 



small eye large eye ("pin") large eye 



(9) (3) (3) (I) 



the 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 colour and hairiness in stocks. It is 

 evident, however, that the conception of the inter- 

 action of factors, besides clearing up much that is 

 paradoxical in heredity, promises to indicate lines of 

 research which may lead to valuable extensions in 

 our knowledge of the way in which the various parts 

 of the living organism are related to one another. 



