130 BOARD OF AGRICULTURE. 



add a branch of study which has of late years risen to the rank of 

 a science, microscopy. A clear understanding of the laws relating 

 to the diseases of plants presupposes familiarity with the sciences 

 just named, as well as close and prolonged investigations in the 

 laboratory and on the farm. Very little attention has been devoted 

 in this country to the subject, partly from lack of material for 

 methodical study, and partly from lack of opportunities for field 

 experimentation. The subject is an obscure one. Nearly all the 

 light which has been thrown upon it has come from the libraries 

 and the laboratories of European botanists and chemists. The 

 facts which I present now have been derived from a survey of the 

 English, French and German works upon the diseases of plants, 

 and I wish to be distinctly understoo d at the out-set as refraining 

 from expressing my own opinions relative to disputed statements 

 and contradictory hypotheses. I shall bring before you the trust- 

 worthy records of foreign observations, and leave you to draw 

 your own conclusions in regard to matters still in dispute. 



Let us first gain a clear idea of a disease. The word disease 

 originally meant a want of ease, and in this sense it is used by an 

 early English writer. It is so employed in Wickliffe's translation 

 of the New Testament, in the 33d verse of the 16th chapter of 

 John, "in the world ye shall have disease," that is want of ease, 

 but in the translation which we all use, it reads " in the world ye 

 shall have tribulation." The word disease has now a wider 

 signification than this. It is applied to maladies and morbid 

 states of the body. The word is now defined by medical writers to 

 mean a derangement of the normal function of any part of the body, 

 thus being used almost synonymously with the term "disorder." 

 Normal means according to a standard or a rule ; and the har- 

 monious working together of the functions of all parts of the body, 

 according to the normal or standard, gives us what we know as 

 health. Now when we establish a straight line as a standard of 

 health, it is plain that we may have deviations above as well as 

 below this line. Do not understand me to say that a person can 

 be too healthy, that is impossible. It is, however, obvious that 

 any part of the organism may do more than its proper work, may 

 be too active in the discharge of its function, and this deviation 

 from the line of health is above it, and is, as truly, a disease as if 

 the same part of the borly failed in activity. When the eye fails 

 even in the brightest light to distinguish objects, we say that the 



