CHAPTER IX 



THE TREA TMENT OF LEA VES 



§ 38. What is the effect of injuries to the leafy tissues? 



From what has been previously stated with regard to the work 

 done by the leaves, it follows that every injury to the leaves 

 means a decrease in the amount of new material formed. The 

 removal of the smallest amount of leafy tissue entails the 

 loss of some of the cells which should build up new organic 

 matter. 



As the veins of each leaf lead downwards through the leaf- 

 stalk into the shoot, and as the soft bast and bundle sheath 

 conduct downwards the organic matter formed in the leaves, 

 the diminution in the organic matter formed will first make 

 itself felt in that portion of the shoot which is close to the 

 insertion of the leaf. If the shoot still requires the food 

 material for itself, the injury to the leaves will cause the shoot 

 to be less completely developed, i.e., will cause it to remain 

 short. 



This is the explanation of the success which accompanies 

 the removal of the tips of leaves of a shoot before it has done 

 growing. The removal of the upper portion of the leaf causes 

 the adjoining internode to remain short. Peaches regularly 

 produce premature branches, i.e., the buds which have just been 

 produced in the axils of this year's leaves grow out immediately. 

 These premature {'proleptic^ shoots have the peculiarity that 

 their lowest internode grows several inches in length instead of 

 remaining short, as it does in branches which are produced 

 after a long resting period. The lower leaves and eyes of these 

 premature shoots are, therefore, also several inches from the 

 parent shoot. That is, however, a fault in trained trees in 

 which one of the objects to be attained is to have the fruit as 



