HARRIS AND AVERY: MORPHOLOGICAL VARIATIONS 117 



a compared with 9.77 per cent, with five and six leaflets in the 

 nrmal controls. 



Taking the average number of leaflets per plant as a basis of 

 cmparison between the abnormal plants and their controls we 

 fid the results in TABLE IX. 



TABLE IX 

 MEAN NUMBER OF LEAFLETS IN SEEDLINGS OF VARIOUS TYPES 



Note (a) that for each type of normality the average number 

 o leaflets is greater in the abnormal individuals than in the nor- 

 iil, and (&) that the difference between the abnormal class and its 

 cntrol is far greater in the case of the plants with three cotyledons 

 tan in those in which the abnormality in the cotyledonary whorl 

 cnsists merely in the separation of the two cotyledons. 



Thus the results for number of leaflets substantiates the con 

 cision based upon number of leaves. 



Evidently, however, the number of leaflets is to a great extent 

 ctermirted by the number of leaves. The problem now arises: 

 r e there differences in the average number of leaflets per leaf in 

 te abnormal and normal individuals? 



Means and their differences have been determined, but are 

 s slight that conclusions must be deferred until further series of 

 eta are available. 



Just one other method of dealing with the problem of the cor- 

 rlation in structural variation may now be considered. 

 : Number of leaflets is, in the materials dealt with, practically 

 a integral variate. In examining a large series of plants those 

 Uh partial division of a leaflet, representing transition stages 

 Hween a leaf with n and one with n + I leaflets are sometimes 

 fund. Such cases are, however, relatively rare. The lobing of 

 1e leaflet has therefore been disregarded in the foregoing treat- 



