84 QUINCE CtJLTUKE. 



take in a dozen of them at once. Hence the ease with 

 which the disease may be spread. 



Prof. J. 0. Arthur, botanist of the New York Agricul- 

 tural Station, who has given much time to the study of 

 this disease, suggests that "The bacteria escape from 

 the tissues in the slimy drops that ooze out from the 

 diseased parts, especially in damp weather. They are 

 washed off and freed from the viscid part by rains, and 

 upon becoming dry are taken up by the winds. Being 

 now suspended in the air, a damp day, dewy night, or 

 light rain would bring them in contact with the delicate 

 surface tissues of fresh cracks or wounds, in the most 

 favorable way to introduce the contagion. This is quite 

 in accordance with the fact that the disease usually starts 

 at the ends of the branches, but also appears sometimes 

 on the larger limbs, and even the trunks. It also ex- 

 plains the fact that the rankest growers are most subject 

 to attack, these exposing more tender surfaces, and, upon 

 the disease obtaining a foothold, furnishing more succu- 

 lent tissues." Insects are almost sure to carry the disease 

 wherever they go, after contact with these exudations. 



The theory that ascribes the blight to bacteria is so 

 well proved that it is needless to notice the older theories 

 which obtained before 1880, when Prof. T. J. Bun-ill, of 

 Illinois, began experiments to demonstrate this. "The 

 bacteria connected with pear blight are all of one kind, 

 and of only one kind : not the bacteria of putrefaction 

 or of animal diseases, but a kind that have never been 

 found anywhere except in blighted fruit trees. These 

 have been named Micrococcus amylovorus. The former 

 word, the generic name, means very minute bodies; the sec- 

 ond, or specific name, means that they are lovers of starch. 

 They are very minute vegetable organisms, and live on 

 starch or similar substances. They multiply by dividing 

 into two, like the figure 8; these divide again, this process 

 of division and subdivision going on very rapidly." 



