The Potato Disea.se. 515 



the fungus developed its mycelium with remarkable rapid- 

 ity and fruited most abundantly, when he kept the diseased 

 haulms, which were the subjects of his study, in a dish 

 between wet pieces of calico, or in a confined and moist 

 atmosphere under a bell glass. So every farmer has learned 

 to fear warm and wet weather, muggy weather, as condu^ 

 cive to the potato rot. The humidity of the atmosphere is 

 entirely beyond our control, but that of the soil may, by 

 judicious selection or by drainage, be regulated. Too abun- 

 dant and fat manures tend to produce these fatal conditions, 

 and are, therefore, wisely avoided. Before the days of the 

 rot, potatoes were grown on almost any land that was dry 

 enough to be plowed ; but since then land dry enough for 

 corn is allotted to them. 



The ravages of the fungus parasitic upon the vine have 

 been nearly abated by dustings of sulphur ; and it is quite 

 possible that similar applications, harmless to the potato 

 plant, but fatal to its parasite, will be found out. 



The potato disease is an old foe ; doubtless, had observa- 

 tions been carefully made, and accurately recorded, all 

 along through the history of the potato, science would now 

 be able to declare with assurance, that this Peronospora, in 

 some form of its manifold life, had clung to it, since its 

 first introduction into Europe. It is an enemy that is 

 always lurking near, ready to work its course of mischief, 

 whenever the conditions of earth, air and plant are favor- 

 able to its growth. 



