278 PRINCIPLES OF GARDENING. [CH. VIII. 



To consider that because a bud, a brancli, or a root 

 is diseased, that the cause of the disorder is to be 

 sought for there, is as sensible as to suppose that 

 every local pain endui'ed by the human frame arises 

 from a disorganization of that part. On the con- 

 traiy, we Imow that the diseases of animals arise al- 

 most universally from the stomach; and, as Addi- 

 son remarked, " that physic is generally the substi- 

 tute for temperance or exercise." The functions of 

 the stomach, by whatever cause deranged, render di- 

 gestion imperfect, and the secretions defective ; the 

 bile is superabimdant or deficient in quantity, and 

 head-ache is the result ; the liver is diseased, and it 

 causes a pain the most acute between the shoulders ; 

 the blood is ill elaborated, and eruptions are thrown 

 out on the surface of the body. With plants it is 

 the same. It may be laid do-«ii as an axiom, ^rith- 

 out exception, that all vegetable diseases, unpre- 

 ceded by external injmy, arise from the unhealthy 

 state of the sap — a state brought about conjointly or 

 separately by the improper food imbibed, and the de- 

 ranged digestive power of the leaves and other or- 

 gans. That this is so will not appeal' strange, when 

 we reflect, that from the sap all parts of the plant 

 are formed, and are continually increased in number 

 and size. The solid substance of the wood, and the 

 temporaiy tender blossoms are alike extracted from 

 that circulating fluid. If the constituents for tliese 



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