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growing-places appear to be the grapes, whose succulent 

 saccharine juices supply it with abundant nutriment. It 

 shows itself principally upon the young grape when about 

 the size of a pea. The slightest injury from a touch or 

 an insect, affords it a basis of propagation, and once 

 established, it increases with amazing rapidity, frequently 

 blasting the hopes of the grape-harvest over many dis- 

 tricts. Its effect upon the grape is to absorb the juices 

 of the superficial cells of the cuticle, which consequently 

 cease to expand with the pulp of the fruit ; it then 

 bursts, dries up, and is finally destroyed. To the naked 

 eye the plant appears a mere effused, indefinite, white 

 patch ; inider the microscope it resolves itself into a 

 collection of little, downy heaps, with egg-like sporidia 

 arising from the necklace joints of the threads. 



The following report of its devastating effects may be 

 interesting: "In 1847, the spores of this oidium 

 reached France, and were found in the forcing-houses of 

 Versailles, and other places near Paris. The disease soon 

 reached the trellised vines, and destroyed the grapes out 

 of doors in the neighbourhood, and continued to extend 

 from place to place ; but, until 1850, it was chiefly ob- 

 served in vineries, which lost from this cause, season after 

 season, the whole of their crops. Unhappily in 1851, 

 it was found to have extended to the south and south- 

 west of France and Italy, and the grapes were so affected 

 that they either decayed, or the wine made from them 

 was detestable. In 1 852, iheOidium Tuckeri re-appeared 

 in France with increased and fatal energy ; it crossed 

 the Mediterranean to Algeria, has shown itself in Syria 

 and Asia Minor, attacked the muscat grapes at Malaga, 



