AND FARMING PRODUCE. 315 



thence cut off, the haulms dry up, and wither 

 away prematurely. The same is the case with 

 tubers. Being deprived of their due supplies of 

 generative sap, they neither attain their full 

 growth, nor contain full equivalents for thorough 

 maturation. 



It hence appears, that the virus commences 

 with the Botrytis, and is the result of its action 

 and deliquescence; and not the predisposing 

 cause of its existence. For the diseased fluid 

 seems not to dissolve the cellular tissue previous 

 to the appearance of the fungus, nor does the 

 fungus spring from the virulent fluid on the 

 blistered haulm afterwards. And dryness, stops 

 the progress of the blight, by withdrawing the 

 condition necessary for the spread of the fungus. 

 I have leaves of potatoe plants in almost every 

 stage of the disease, when the blight was arrested 

 by the dry weather, which commenced on the 

 25th of August of last year. A crop of potatoes 

 was saved almost entirely by this change in the 

 weather, on a farm adjoining my cottage. Dry 

 air promotes the transpiration and aeration of the 

 juices within the leaves of plants, and stays the 

 growth of all fungi. Hence, dry weather is a 

 check to the blight in all its stages. 



