Communications. 



273 



the slightest appearance of blight was manifested, in any instance, 

 on them. The writer further states that the conditions of plant- 

 ing, manuring and soil were practically the same in each case. 

 Facts similar to these have been collected from time to time, and 

 form an important point for further examination." 



It will be at once admitted that in the metamorphosis of 

 varieties as well as species, a change of cell-structure is brought 

 about, and, as a natural consequence, their cell-product will 

 correspondingly change more or less. The sap or juices may 

 change materially in the proportion of their composition and thus 

 become favorable or unfavorable as a nidus for the fungus to 

 propagate in. To suppose that a fungus, which is a plant, is not 



Fio. 



Section of Potato phowixo Stem and connection with Etes; Cells 

 ENCLOSING Stauch; Rri'TiRKD Cells and escaimnu tiTAitcii Gkains. 



thus affected would be erroneous ; all our experience demonstrates 

 that all plants and animals are affected more or less by the nature 

 and condition of their food and other considerations, such as their 

 habitats. Thus we find in practice that at the present day on the 

 sandy soils of New Jersey, the blight is unknown, while in the 

 moist New England States it is seldom absent, and the plague still 

 continues to be very destructive in Great Britain and Ireland, 

 where the climate is very moist. Last year's potato crop suffered 

 severely from blight in the above mentioned countries. Where 

 the foliage of a potato is affected with Botryils infesians its myce- 



18 — HORT. 



