DISEASES AND INSECTS. 375 



and life of man is greatest when he lives in a 

 condition of simplicity, supplying only the nat- 

 ural wants of his appetites ; but when he places 

 himself under artificial conditions, he loses a 

 part of his hardihood, becomes more susceptible 

 to disease in its various forms, and recourse is 

 had to various means for restoring and main- 

 taining, as well as may be, the operation of well- 

 known physical laws, which are necessary to 

 health. It is the same with plants. When 

 growing in their natural condition, they are 

 subject to few diseases ; but when placed under 

 artificial conditions, and made tender and sus- 

 ceptible by injudicious hybridizing, crossing, se- 

 lection, propagation, etc., they become peculiarly 

 liable to disease, and means must be used here 

 also to restore and maintain the operation of 

 those physical laws which apply to the case. 

 These brief allusions sufficiently show the gen- 

 eral analogy between animals and plants in re- 

 spect to those physical laws which govern life. 

 If the reader appreciates it as he should, he will 

 learn to study the diseases of the vine for him- 

 self, and not look upon them as a sort of fatal- 

 ity not to be overcome. 



We will now confine our remarks to the vine. 

 The vine, like man, is subject to disease ; and as 



