273 Wisconsin State Hoeticultural Society. 



small pencil brush remove the spores from an infected leaf, place 

 it on a slip of glass three inches bj one in diameter, add a drop 

 of water, and place over the whole a very thin glass cover of the 

 kind generally used, and view under a magnifying power of. 

 about five hundred diameters, when their structure and peculiar 

 life-like motions will be observed. These spores multiply with 

 great rapidity during wet weather. The offspring of a single 

 spore will probably exceed forty millions in twenty-four hours. 

 This explains the rapid destruction of the potato plant when 

 exposed to the ravages of this fungus. Large premiums have 

 been offered from time to time for a remedy, but as yet no suc- 

 cessful mode has been found to fully restore the potato to its 

 wonted vigor. With this end in view many plans have been 

 tried; new varieties from the seed tested, and the changing of 

 soil, climate and fertilizers proposed, and it is now commonly 

 believed by the present scientific cultivators of the potato in Great 

 Britain, that varieties which mature very early or very late in the 

 season will escape the blight. This would indicate that the con- 

 dition of the sap of the potato has special reference to the growth 

 of the fungus. The scientific committee of the Rojal Agricultural 

 Society of England also favors the planting of early and late 

 varieties. 



Many mycologists assume that the Botrytis infistans is wholly 

 the cause of the blight, while acknowledging that a moist, warm 

 atmosphere greatly accelerates the growth and germination of the 

 fungus, but evidence is not wanting to show that in some cases 

 where two distinct varieties have been planted together, one of 

 them only was blighted, thus showing that some peculiar condi- 

 tion of the plant affected was favorable to the growth and repro- 

 duction of the fungoid spores. The following case illustrates this 

 fact: 



" Mr. Martin McKinzie, of Boston, Massachusetts, wrote to the 

 department under date of November 1, 1872, stating that, in a 

 field near his residence, Early Rose and White Jackson potatoes 

 were planted the preceding season, adjoining each other; the first, 

 or Early Rose, proved nearly an entire failure, from blight fungus 

 while the second, or Jackson Whites, grew to perfection. Not 



