BLIGHT AND OTHER TREE DISEASES. 105 



a few inches, and sit with his neck, for instance, exposed to 

 a cold current of air in winter. Almost certainly, in a few mo- 

 ments he would begin to sneeze, nature's danger signal, and 

 if he remained there a while, would "take cold," as we call 

 it ; but, really, the man would take nothing. The cold air, 

 blowing on a limited part of his body, broke up his natural 

 heat equilibrium, which we call "health," in the human sys- 

 tem, thereby furnishing an unexplained condition, highly fa- 

 vorable to the rapid development and multiplication of the 

 influenza or "cold" germs in all human beings. But the re- 

 sult will not necessarily be a "cold " in the head or neck ; for 

 the bacteria will develop at the point of least resistance in 

 the system, and may settle on the lungs, resulting in pneu- 

 monia or consumption, or they may attack the nervous system 

 in the form of neuralgia or rheumatism, and often the bowels. 

 But, again, let a person or a number of them, enter a room 

 with a hot stove fire, closing all openings, and shortly most 

 or all of them will also begin to "take cold." Here, again, 

 we find the natural heat condition, or equilibrium, of their 

 bodies broken up by an abnormal high temperature and ex- 

 hausted atmosphere; but they "took" nothing, for, had the 

 room been ventilated and not over-heated, the "cold" bac- 

 teria in their blood would have been unable to develop, just 

 as the brown-rot bacteria could not do so on my Terry apples, 

 but did on the Georgia Terry, grown under different conditions. 



Admitting the above facts as to man, and reasoning from 

 analogy, is it not also highly probable that bacteria exist 

 naturally in the sap or blood of plants and trees? It is plain 

 that there is a marked similarity between the diseases of man 

 and of trees. We see the quick and fatal work of cholera dupli- 

 cated in "fire blight" of the limbs and leaves of the apple, 

 pear and English walnut of California, the slow, insidious 

 methods of consumption in the "yellows," while black-knot, 

 root-rot, crown-gall and root-knot give perfect counterparts to 

 the various forms of scrofula. 



May we not go still further, and declare that every known 

 form of mildew, rust and other plant diseases are naturally in 

 the plants themselves, and, under normal conditions, entirely 



