Dwarf Apples. 



I. Dwarfing in General. 



Effect of checMng the movement of sap. — All fruit trees are pro- 

 vided with certain well-defined courses through which the sap 

 passes to every part of the plant. After the roots have taken in 

 the water with its freight of dissolved plant food, the crude sap, 

 as it may then be termed, enters a definite course which eventu- 

 ally brings the nourishment to the parts in which the materials 

 are used for constructing plant tissue. There is no circulation of 

 sap in plants in the sense in which there is in animals, no definite 

 tubes through which it flows. It passes through the plant tissues 

 by a process of absoirption. The regions in which this transfer 

 takes place will become apparent upon consideration of a few 

 common facts. 



Let us suppose a very common case. Labels are frequently 

 secured by means of a wire which surrounds either a branch or 

 the trunk of the tree. It is no unusual occurrence that such 

 labels are neglected, and as the stem increases in size, the wire 

 becomes imbedded in the bark. This forms a constriction about 

 the stem, and the connection between the parts above and below 

 the wire is more or less effectually destroyed, especially in the 

 outer portions. As the wire becomes more deeply buried, an 

 unequal growth takes place in the adjoining tissue. The stem 

 immediately above the wire becomes abnormally enlarged, while 

 the rate of growth below is greatly lessened or almost entirely 

 checked. • If the wire is not removed, union of the tissues sepa- 

 rated by the jvire may take place, and the tree will be little the 

 worse for the check. More frequently, however, young trees are 

 so severely cut that the increased weight of the top forces the 

 stem to break where it is surrounded by the wire, causing a total 

 loss of this portion. 



Another familiar example may be named. When the trunk of 



