348 



Tricotylous Races. 



position, tlie proportion of tricotyls (that is to say all 

 the aberrant forms of the series) being about 10%. 



Or in % 



If we wish to make ordinates for the various degrees 

 of cleavage we are met by tlie difficulty presented by the 

 choice of the limits of such arbitrary groups. This diffi- 



Fig. 64. Oenothera hirfella. Intermediate forms between 

 the dicotylous seedling (A) and a tricotylous one (G). 

 The normal cotyledon has been cut away from each 

 plant. Cultivated in 1900. 



culty is partly due to the fact that the stalks of the 

 cotyledons continue to grow for some time after the 

 cotvledons themselves have assumed their definitive form. 



