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not have immediately vegetated on entering the plants, but were probably- 

 carried by the elaborated sap of the leaves and deposited along with it in 

 the cellular tissue. Mr. Berkeley states that, "it seems to him most cer- 

 tain, from observations on those fungi which grow from the tissues of 

 plants, that minute particles, too small to be distinguished by the highest 

 powers of the microscope, must be carried about with the juices, and 

 when fitting circumstances concur, proceed to act upon the tissue with 

 which they are in contact." 



The disease was observed to progress on the Continent of Europe, as 

 in Britain ; it was said in a letter from Bologna, that the geographical 

 limits of the disease, as well as its intensity, had extended in that part of 

 the world very far beyond what they were the previous year. Another 

 most important fact is, that the fungus, which is the cause of the blight, 

 is a species new to cryptogamic botanists. If it had been co-existent 

 with the potatoe in these parts, it is hardly probable that the parasite of 

 so common a plant should have escaped the attention of the botanists of 

 Europe, or that it should not have attacked the potatoe partially in for- 

 mer years, instead of making such an universal onslaught as of late in 

 very different seasons and situations ; for whether the conditions favora- 

 ble to the growth and increase of parasitic fungi, be atmospheric, or an 

 unhealthy condition of the larger plant, we have had seasons when fungi 

 have prevailed to a considerable extent on other plants, and varieties of 

 the potatoe have certainly been in a very unhealthy condition previous to 

 the appearance of the disease, and yet it has been observed to be a plant 

 peculiarly exempt from blights and mildews. It seems, therefore, proba- 

 ble, if not certain, that botrytis infestans is a recent introduction, and if 

 so, this affords a very satisfactory explanation of the remarkable fact that 

 the disease is certainly of modern origin. 



Our next inquiry is a most important one. What are the conditions 

 required for the growth and increase of parasitical fungi, and which have 

 led to such an extensive and unprecedented attack, on one plant only, in 

 so many different countries, under so many different circumstances, and 

 in some instances during several successive years ? Are they some elec- 

 trical or other peculiar unknown atmospheric influences, as stated by 

 Mr. Berkeley, or chiefly an unhealthy condition of the larger plant, as I 

 have ventured to suggest. 



Fungi have evidently not the power to destroy healthy vegetation, if 

 they had, the superior plants on which they prey would shortly be swept 



