VINE MILDEW. 115 



fact for this purpose, to know that it is reproduced by the easy 

 dissemination and rapid germination of its spores which are 

 formed in such prodigious numbers on its fertile stems. 



The Biological Societj^ will remember that I was the first in 

 France, not perhaps to denounce the malady, but to give a 

 description of it, accompanied by its proper name, which was 

 inserted in the Compte Rendu of the Session of May 11, 1850, 

 and in the Bulletin of the first of May of the same year.* Since 

 that period the malady proceeding from the stoves of Versailles 

 extended to the trellises, and from thence to the neighbouring 

 vineyards, till by degrees it has attacked the whole of Europe 

 and has extended even to Madeira. 



Etiological. Were we to judge from the concurrent efforts 

 to throw some light on the origin and nature of the evil, one 

 would imagine that nothing is clearer than the etiology of the 

 vine mildew, that universal pest which menaces the future 

 ■welfare of our vine-producing departments, and which has already 

 produced such disasters. But alas ! we should make a great 

 mistake if we thought so, for there is little agreement on this 

 point. Amongst those who have endeavoured to trace out the 

 source of the evil, there are two principal opinions diametrically 

 opposite. The one assumes that the vines are intimately affected as 

 regards their physiological functions, without however sayingexactly 

 how; and that it is in consequence of their morbid state, attributed 

 sometimes to plethora, sometimes to radical weakness, an argu- 

 ment as we perceive extremely shifty and elastic, that the parasitic 

 fungus is enabled to establish and propagate itself on parts 

 already diseased. Tiie others, on the contrary, amongst whom I 

 am one, attribute to the presence of the Oidium the essential and 

 sufficient cause of all the injury inflicted on the vines and grapes. f 

 Among competent persons who pi-ofess the first opinion we may 

 quote Berenger, Count Brignoli, Baron Cesati, Crocq, Decaisne, 

 Leon Dufour, Guerin-Meneville, Heuze, C. Laterrade, reporter 



* M. Dnpuis has claimed the honour of having first observed it on the 

 borders of the Rhone in 1834, and of having recorded it in the Annals of 

 the Agricultural Society of Lyons for 1839. This is possible, but it still 

 remains to be shown that M. Dupuis was acquainted with the fungus 

 which either causes or accompanies it. 



+ Mohl, in his first memoir (see my translation in the Memoirs of the 

 Imperial Arjricidtural Society, Part I., 1852), compares the action of the 

 Oidium on the grapes to that of a parasite of another order, Achlya pro- 

 lifera Nees, or Saprolegnia ferox Kiitz, upon fresh-water fish. See Rohin 

 Hist. Nat. des Vege't. j'^arasites suv les Animauxvivans. Nouv. ed., 1853, p. 372. 

 See also this journal, April, 1852. 



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