862 
Journal of Agricultural Research 
Vol. XXI, No. II 
Another phase of the variability of the laterals is shown by the graphs 
in figure 5, which show the frequency distributions of laterals I and V 
in the pruned class and of the apical shoot in the unpruned class. The 
graphs for the apical lateral in the unpruned class and for lateral I are 
fairly symmetrical but have a skewness in the direction of the higher 
values. The graph for the lateral V is very asymmetrical because a dis¬ 
proportionate number of variants fall in the upper classes. Each of 
these graphs indicates that the variability in the length of the laterals 
is not a chance phenomenon, but that it is a function of their position 
on the mother shoot. The tendency of these factors is to produce 
more long laterals in each class than would be found if their length were 
/so 
too 
6Q 
Fio. 5. Frequency distributions of the mean lengths of certain laterals. The solid line represents lateral I 
on pruned mother shoots; the broken line, lateral V on pruned mother shoots; and the dots and dashes, 
the apical lateral on unpruned mother shoots. 
determined by pure chance. That this influence is inherent in the 
tree and not due to the operation of pruning is shown by the same 
tendency in the frequency distribution of the laterals arising from the 
apical buds on the unpruned mother shoots. 
II. DOMINANCE OF THE DISTAL LATERALS OF THE PEAR TREE 
It is hardly necessary to mention again that the distal lateral on a 
vertical shoot is usually larger than any other lateral growing between 
it and the base of the mother shoot. It will be profitable to study the 
problem somewhat further with the hope of gaining more light on the 
causes of this characteristic type of growth. 
An inspection of the tables giving the size of laterals on the mother 
shoots shows that, as a rule, the length of the distal lateral has some 
sort of inverse ratio to the length of its mother shoot. The relation¬ 
ship was determined by computing the coefficient of correlation between 
I 
I 
