SECRETARY'S REPORT. 59 



We now proceed to speak of the proper method to be adopted 

 in the investigation of disease. At present, if a crop fails, every 

 sufferer from its effects starts up with a theory based upon a 

 single fact which lie may have observed, which sets at rest, in 

 his mind, all necessity for farther examination, each theory in 

 turn jostling its neighbor, and each destined to be overthrown 

 by future experience. 



Thus the ignorant man sees for the first time upon his plant 

 an insect, which probably has always shown itself, but has 

 escaped his observation, because his attention has not been 

 drawn to it, and he examines no farther, but at once proclaims 

 himself to the world as the discoverer of the " undoubted cause " 

 of the disease. Another notices the access of disease conse- 

 quent upon a sudden atmospheric change, and this satisfies 

 him, while still another — his whole attention directed as a scien- 

 tific man to certain obscure forms of vegetable life — finds a 

 fungus growth which has heretofore been unnoticed, and he, 

 like the others, rides his hobby into the midst of the battle, all 

 equally forge ting that while each of their theories may, in par- 

 ticular instances, be correct, they only point to certain exciting 

 causes, leaving still untouched the predisposing causes which 

 alone are of great value in the formation of a true theory 

 which may lead to important practical results. To investigate 

 vegetable disease, then, it is important to examine it carefully 

 in many different localities, to record at each examination 

 every different appearance presented, the part of the plant 

 affected, the character of the soil in which it grows, and the 

 method of cultivation applied to it. The character of the 

 season should also be fully considered, and no attempt to form 

 a theory should be made until such an examination has been 

 repeated in successive years. By pursuing this course, it will 

 usually be found that some common cause has been acting upon 

 all the plants affected, and at least an approximation to the 

 truth may be obtained ; while hastily formed theories only tend 

 to mislead and blind the observer to many important facts, 

 often quite as essential as those upon which the theory is based. 



To give a practical application to what has been said upon 

 the last topic, we would call the attention of orchardists to a 

 disease of very malignant character, which may be found in 

 many nurseries and young apple orchards, and which, if not 



