510 State Board of Agriculture, &c. 



necessary to the success of these zoospores that they should 

 find their way to open breathing pores ; for they are capa- 

 pable, when set free, of at once corroding, boring and 

 entering the epidermis or close outer skin of the leaf, or 

 even that of the stalk. When they have ceased to move, 

 their tails or cilia disappear ; and, having burst at one. end, 

 a transparent tube is protruded, which is a similar myce- 

 lium, in every respect, to that produced by. tlie simple spore, 

 and which grows, branches and fruits in precisely the same 

 manner. 



Now, though all this had been known respecting the 

 potato fungus, botanists had been sensible, for many years, 

 that much still remained involved in mystery. The great dif- 

 ficulty which beset them was to account for the winter life 

 of the fungus. Simple-spores and swarm-spores are lost in 

 the production of the mycelium ; and this fine, thread-like 

 material cannot, of course, survive the frosts and rains of 

 winter, and must utterly perish with tlie perished leaves 

 and stalks. How, then, is tlie fungus preserved through 

 the winter ? From what beginning, however small, does 

 its life start the succeeding year ? These were questions 

 which no fungologist was able to answer. Informed on 

 this point, the cultivator might head off the disease by 

 avoiding the germs, or by attacking it in its infancy. For 

 all the knowledge thus far acquired, this important crop lay 

 much at the mercy of its foe ; the great difiiculty in tlic treat- 

 ment of the disease arising from the fact tliat the fungus, 

 as far as it was now known, existed within the infested 

 plant, where it could not be got at. 



Within the past two years, however^ all that remained 



