550 



THE NATURE OF THE GROWTH RATE 



time of measurement had an approximate value of 25. There are 

 fluctuations from this value, but the trees showed little tendency to 

 increase in variability until near the end of the growing period. 



The Juglans nigra trees from which all laterals were removed in the 

 spring before growth began made the same type of growth as their 

 unpruned neighbors, but in every case their mean height was less. 

 The commonly accepted belief is to the effect that removing the lat- 



150 



130 



no 



a> 70 

 50 



cv 



30 







20 



40 



60 80 



Time in days 



Fig. 2. The growth of Juglans nigra trees. - 



100 



120 



140 



increase in mean height 



of unpruned trees. increase in mean height of trees from which laterals 



had been removed. — . — . — Coefficient of variability of mean height of un- 

 pruned trees. 



eral branches from a plant increases the growth of the main axis, but 

 the results of this work directly contradict the above mentioned 

 belief. 



The mean grovdng period of the pruned seedlings was 122 days, 

 or practically the same as that of the unpruned seedlings. Compari- 

 son of the figures shows that the pruned seedlings increasingly lagged 

 behind their unpruned neighbors as the season advanced. 



