240 TRANSACTIONS OF THE HOETICULTURAL 



course, runs out and is diffused among the tissues, and its nutritive 

 condition lost. The putrefactive condition, which soon follows, gives 

 rise to fungoid growth, or forms a pabulum for bacteria. If the 

 theory that certain organisms in the atmosphere are the cause of 

 many of the forms of disease with which plants are afflicted, then 

 we have but little hope of ever learning how to avoid their depreda- 

 tions. While if the causes are physical conditions, as I have indi- 

 cated, then it is quite within the province of man to supply proper 

 conditions to maintain the health and usefulness of his plants. For 

 our orchards, the most important of these is situation. A northern or 

 northeastern slope of land is the most favorable, as such a situation 

 will not be subject to the solar heat that would pour upon a southern 

 or southwestern slope. Proper cultivation, and drainage to prevent 

 a superabundance of moisture is also important. Many of our use- 

 ful plants thrive in shady localities, and so, by planting timber belts 

 around, or planting trees among fruit-bearing trees, good results 

 may be obtained. With a congenial location, good cultivation, care- 

 ful drainage, and a constant supply of plant food, the horticulturist 

 can plant with reasonable assurance of securing health, vigor, and 

 an abundant fruitage from his plants and trees. 



Prof. Burrill — This is not the time to discuss these questions, 

 but the idea advanced by Dr. Humphrey, that bacteria are the result, 

 rather than the cause of disease, I think incorrect. Opinions may 

 not be, and often are not worth much, but when sustained by facts, 

 they become valuable. I will give the result of an experiment that 

 I conducted, that to my mind, is conclusive : 



The broom-corn growers of Champaign County have been 

 troubled with a disease of the stalk caused, as I supposed, by bacte- 

 ria. To test the correctness of my conclusions, I took a stalk and 

 marked it off into checks, and with a camel's-hair brush, painted 

 every other check with pure beef broth, in which these organisms 

 had been grown. The result, in nearly every case was, that on the 

 checks on which the fluid was placed, the disease developed, while the 

 others were exempt. The microscope shows that the red appearance 

 of the diseased stalk is caused by myriads of these organisms which 

 under the glass have the appearance of minute red points. I have 

 tried this experiment over and over again, and always with the same 

 result. It is one of the most direct and conclusive experiments I 

 have ever made. 



