o06 State BoAiiD of Agriculture, tfcc. 



ino; the price of the important commodity of silk, in all the 

 marts of the world. The plant attacks the interior of the 

 ■caterpillar, which it finally kills, and twenty -four hours after 

 its death the matured fungus appears under the microscope 

 like a wide forest on the surface of the worm, which looks 

 to the naked eye as thouorh covered with fine flour. All 

 remedies devised against the muscardine had proved fruitless, 

 and just as it was disappearing it was i-eplaced by the spot^ 

 <ix j)ehnne^ which some naturalists consider to be, also, of 

 vegetable origin. 



Another fungus, closely related to the last, Peronospora 

 infestans, causes the potato disease, of which this paper 

 treats. This disease was first noticed near Liege in 1842. 

 It rapidly became very malignant, and in a few years had 

 spread into all countries where this important esculent is 

 cultivated. The damage sustained by Great Britain and 

 Ireland in 1845, from this cause, was estimated at not less 

 than £21,000,000, and in the following year it was proba- 

 bly twice tliat amount. Adapted to furnish, in large quan- 

 tities and at small cost, a supply of food, the potato had be- 

 come to the masses of Ireland their staff of life ; and when the 

 rot had turned their floury food into a black and reeking mass 

 of puti-ef action, famine set the Irish hive swarming. For more 

 than a decade the broad stream of Irish emigration poured to 

 our American shores. It supplied to the wide spread impulse 

 of railroad building, which was beginning to move our na- 

 tion, the needed means of labor ; it added to the heteroge- 

 neous compound of our society a new and strong element ; 

 it formed in our metropolis a party which long controlled 

 its government ; and having re-colonized the Eastern States, 



