Sept, i, 1921 
Growth in Branches of Young Pear Trees 851 
I. GROWTH AND DIFFERENTIATION OF LATERALS 
The characteristic growth of laterals and fruit spurs on the mother 
shoots is to be regarded as an expression of their capacity to develop 
under the influence of the various internal and external factors at work. 
An analysis of their nature and variability ought to throw some light 
upon the laws of growth. 
Such an analysis will involve an investigation of at least two phases 
of the laws of growth—first, the total quantity of shoot wood produced 
upon the mother shoots, and secondly, the differentiation found in the 
laterals produced upon the mother shoot. At all stages of the inquiry 
Fig i.—F requency distributions of buds on mother shoots. The solid line indicates distribution on pruned 
shoots and the broken line distribution on unpruned shoots. 
it will be profitable to compare the growth produced on the pruned 
mother shoots with that produced upon mother shoots of similar age 
which received no pruning. 
It will doubtless seem to some readers that the investigation treats 
the mother shoots to too great a degree as independent organisms. 
The only reply to such a criticism is that it seemed impossible to treat 
them in any other way. While correlative influences undoubtedly exist 
between the different mother shoots, it seems at present impossible to 
evaluate them. By using a sufficiently large population, it is probable 
that such correlated influences are to a large extent equalized. It may 
be stated, however, that the upright shoots on young pear trees are 
sufficiently uniform for all purposes of the present investigation. 
