74 STUDIES IN INDIAN TOBACCOS. 



Table XITI gives the results obtained in the cross Type 9 

 (non-decurrent) x Type 51 (with an average of 6 cm.). The 

 Fj was intermediate betw een the parents and the ¥, covered the 

 whole range between non-decurrent forms and those like Type 51. 

 Several of the plants classed as non-decurrent in the ¥.,, however, 

 gave rise to forms with decurrent laminas later (cultures 738 and 

 745). This maybe due to the fact that in the early investigations 

 the number of factors involved was not realized and no measure- 

 ments of less than .5 centimetres were made. Great differences 

 were observed in the F^ generations, c.t., ^the cultures 738 and 

 132, but none of the cultures proved uniform. In 1912, unfortu- 

 nately all plants in which the decurrent portion was shorter 

 than 5 mm. were again classed as non-decurrent. Cultures 

 738 and 694 were continued to the F^ generation. The results 

 obtained from culture 738 will be considered first. Two plants 

 which appeared similar to Type 9, were chosen for future 

 cultivation, and four plants whose leaves Avere decurrent to 

 varying amounts, 5, 7, 11 and 15 mm. Of the two cultures with 

 non-decurrent leaves, one bred true and resembled Type 9. 

 The other was a heterozygote. A detailed examination of 

 Type 9 shows that occasionally the method of insertion of the 

 leaves caused the lamina to be attached to the stem for about 

 3 mm. This makes it almost impossible to distinguish pure 

 non-decurrent forms from the Fi between non-decurrent leaves 

 and those possessing the smallest factor for a decurrent lamina- 

 In 1913 most careful measurements of all plants have been 

 made especially in those cases where the value was below 

 5 mm. Three careful determinations were made in the case 

 of all the cultures derived from 738, and the mean of these form 

 the data given in Table XIV. The limits, within which the 

 splitting takes place, are so small that it is very difficult to obtain 

 really reliable information as to the extent and number of the 

 factors, but there is no doubt of the difference between the 

 cultures. It appears probable that two factors are involved, 

 one giving a length of about .5 or .7 cm. ; the other about 1.1 cm., 



