GABRIELLE L. C. HOWARD. 63 



conditions were so unfavourable as to greatly stunt or dwarf the 

 growth of the plant. It is possible, however, that the length 

 of the growth period may have some influence. As stated on 

 page 38, in 1913 a portion of the parent cultures were grown 

 too close to a hedge and developed very slowly in consequence. 

 These plants, when they did attain maturity, all had an 

 abnormally large number of leaves. For instance, Type 51, 

 instead of possessing the normal number of twenty-seven to 

 thirty-one leaves, had thirty-one to thirty-five leaves, and a 

 similar increase was noticeable in Type 35. Moreover, in 1913, a 

 late season, the average values of all the parents was about one 

 leaf greater than in 1912. Again, in 1911, another late 

 season, the average value of Type 51 agrees with that of 1913. 

 In the absence of further evidence this can only be put forward 

 tentatively. The ordinary fluctuations of season have no 

 appreciable effect. The number of leaves per plant apart from 

 these abnormal individuals appears to be a very definite inherit- 

 able character. 



Much attention has been paid, in the course of these 

 investigations, to the question of a correlation between the 

 the number of leaves and the height of the plant ; but it is quite 

 clear that each can be inherited independently of the other. 

 Some of the shortest plants have the largest number of leaves. 

 Take for instance culture 251 (Tables V and IX) in the Fg genera- 

 tion of Type 16 X Type 35. This culture is uniform as regards 

 height (av. 50.7 cm.) and uniform as regards leaves (av. 30), 

 that is, it has a greater average number of leaves than Type 51, 

 of which the mean height is 195.5 cm. Culture 190 of the 

 same cross has an average height of 102.1 cm. and the average 

 number of leaves is thirty. Such instances might be 

 multiplied indefinitely. Cases also occur in which the culture is 

 uniform as regards height, but not as regards number of leaves 

 per plant (for example, 740 in the Fg generation of Type 9 x 

 Type 51) and vice versa. The fact that, while the height varies 

 greatly with the season, the number of leaves remains 



