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neath it, having the supporting pressure removed, is 

 enabled to follow the same course at the same locality ; 

 and in proportion to the length of the time that the 

 sap continues in excess, is the depth to which the 

 mischief extends, and the quantity of sap extravasated. 

 If the extravasation proceeds from this cause, there is 

 but one course of treatment to be pursued ; sever one 

 of the main roots to afford the tree immediate relief, 

 and reduce the staple of the soil by removing some of 

 it, and admixing less fertile earthy components, as 

 sand or chalk. This must be done gradually, for the 

 fibrous roots that are suited for the collection of food 

 from a fertile soil are not at once adapted for the in- 

 trosusception of that from a less abundant pasturage. 

 Care must be taken not to apply the above remedies 

 before it is clearly ascertained that the cause is not 

 an unnatural contraction of the sap vessels, because, 

 in such case, the treatment might be injurious rather 

 than beneficial. We have always found it arising 

 from an excessive production of sap, if the tree when 

 afflicted by extravasation produces at the same time 

 super-luxuriant shoots. (Johnson's Principles of 

 Gardening 



Professor Lindley, with his usual ability, has traced 

 the progress of this disease as follows : — Gum is the 

 basis of vegetation, and he would not be very wrong 

 who should assert that the whole framework of a 

 plant is a skeleton of gum. This substance seems to 



