90 



MENDELISM 



given in a brief account of the experiments that have led 

 to it. There exists a monstrous form of sweet-pea in 

 which the flowers are malformed and the stigma protrudes 

 owing to the cleft condition of the keel which normally 

 curves it (cf Fig. t6a). From its fancied resemblance to 



Fig. i6a. 

 The " cretin ' .sweet-pea. 



a gaping mouth with a protruding tongue, such a plant has 

 been termed a cretin. The pollen of a cretin was used to 

 fertilise a sterile plant with normal flowers, and all the 

 resulting F^ plants were normal and fertile. Fertility (F) 

 is dominant to sterility (/), and the normal flower (JV) is 

 dominant to the cretin (;/). The cross was so made that 

 one factor went in from each parent. An F, generation 

 was raised from 9 Fj^ plants and consisted of — 



