282 Wisconsin State Horticultueal Society. 



tion there has not been the slightest approach in any of my ma- 

 terial to organisms which might be referred to Pythium. Mr. 

 Plowright; writes: "None of my oospores ever burst and pro- 

 duced Pythium or Pythium-like spores." 



My material has contained a large number of dead mites and 

 aphides, and a few nematoid worms ; the oogonia and threads 

 were to be seen in all parts of the dead insects, but not in the 

 worms. 



Da Barry, in reviewing my observations, says: " Even if the 

 often mentioned warty bodies were hibernating oospores of Phy- 

 tophthora (Peronospora), like the similar oospores of P. Arenaria 

 which resemble them, we should not gain much information bear- 

 ing on these questions, since their occurrence is, at the best, ex- 

 traordinarily rare." This sentence is very erroneous, for bodies 

 which were apparently rare when I first recorded their discovery, 

 were not necessarily so in a state of nature, for on continu- 

 ing the experiments after my first essay was written, the resting 

 spores were produced in myriads, and that, too, within the tissues 

 of a comparatively few leaves. During the spring I have sent 

 mounted preparations of the mature (or almost mature) rest- 

 ing spores to many of the foremost cryptogamic botanists of 

 Europe, but not one has denied their possible identity with 

 Peronospora infestans. 



For more than thirty years our potato crops have been system- 

 atically destroyed by two virulent fungi, viz.: Peronospora 

 infestans and Fasisporium Solani ; these two parasites invariably 

 work in company with each other ; they suddenly, for a few 

 weeks, destroy our crops, and vanish for ten or twelve months, 

 then reappear, and repeat the work of destruction. I claim for 

 my work that it is new, and that it has proved how both these 

 fungi hide and sleep through eleven months of the year. As 

 I have kept the resting spores alive artificially in decayed potato 

 leaves, in water, in moist air, and in expressed diluted horse- 

 dung, it conclusively proves to me that the resting spores hiber- 

 nate naturally in the same manner. The seat of danger from 

 both parasites is clearly in dung-heaps, ditch sides and decaying 

 potato plants. 



