Dwarf Apples. 379 



ceed only in the presence of light. The leaves may, therefore, be 

 considered as one of the most important factors in the nourish- 

 ment of plants. An injury to them is not merely a local matter, 

 but it affects the entire plant economy. 



After the sap has been elaborated by the foliage, it is in proper 

 condition for nourishing any of the growing cells of the plant. It 

 passes to the growing tips and there assists in lengthening the 

 shoots, in forming new leaves, and in producing buds — some of 

 which may be fruit-buds — which remain dormant until the fol- 

 lowing year. It passes to the main branches and the trunks of 

 the plant, and supplies the cells which are forming wood and 

 those which are forming the tissues of the inner bark with the 

 materials necessary to their support and growth. It passes down 

 into the root system of the plant and furnishes the roots with 

 the food required for their proper growth; but if an insufficient 

 amount of food is present the roots are the first to suffer, for it 

 seems that only the part which is not needed by the parts above 

 jrroiind is allowed to go as far as it may towards the nourishment 

 of the roots. 



W" e are now prepared to consider the effect upon a plant of any 

 injary or other abnormal modification. When a plant is girdled, 

 the nourishing sap is prevented from returning to the roots; these 

 must suffer and eventually die. But when only a part of the top 

 of a plant is girdled, the roots need not necessarily be deprived 

 of their proper amount of food, since the remaining branches mav 

 perform their duty without the aid of the girdled portion. This 

 part, however, may show very marked effects of the treatment. 

 The sap is allowed to enter the branch freely; but when it is 

 returning from the foliage it cannot pass the point of injury and 

 we, therefore, find the abnormal growth of tissue which so com- 

 monly results from such mutilation. Yet all the food is not de- 

 posited at the girdle. Girdled branches are frequently the most 

 fruitful ones; in fact, they may be the only ones upon a tree which 

 produce fruit. The branch may be said to be congested with 

 food, and relief from this condition is sought in the production of 

 fruit. 



Girdling may have other effects than to promote fruitfulness. 

 Grapes are girdled not in order to make them more fruitful, but 



