474 SUN-STROKES. 



some atmospheric agency. It is very evident that 

 the destruction of the rootlets cuts off the supply 

 of sap, which is most disastrous. While the death 

 of the tree may not always result, great weakness 

 always follows. This disease is particularly liable 

 to attack newly-planted trees, especially those set 

 in the spring. When this is the case, and the 

 drought continues, the tissue of the whole tree dries 

 up. The best preventive is a well drained and 

 thoroughly pulverized soil, where it has never made 

 its appearance. 



10. Wounds — Vulnera. These are more or less 

 injurious, according to their nature. If a large 

 limb has been cut or broken down, the inner wood, 

 which has lost its vitality, commences immediately 

 to decay; and, unless it is prevented, it extends 

 through the old wood of the tree. To prevent this 

 loss of mechanical strength, it is necessary to cover 

 all wounds which penetrate deeper than the vital 

 wood with grafting-wax, paint, or some other ma- 

 terial, protecting the wound from immediate contact 

 with the air. If the tree is healthy, the new or vital 

 parts soon extend over it. 



Cattle should not be allowed within the precincts 

 of a young orchard, since they are likely to rub 

 against and break the limbs. Mice or rabbits often 

 totally destroy trees by gnawing off the bark around 

 their base during the winter. Thus, when the sap 



