VINE DISEASE. 51 



kind of plant, which is endowed with several reproductive organs, it is 

 sufficient to consider those polysporous fruits which I have already 

 mentioned, and which vary so greatly in form, as to present all the 

 possible intermediate stages between the spores of the pretended Oidlum 

 and the ascophorous conceptacula of the Erysiphes^ which latter are the 

 most perfect organs of reproduction granted by nature to these Fungi. 

 These same polysporous fruits, being found at once among the soi-disant 

 O'idiums, as peculiar parts of their strings of spores, and among the 

 fertile Erysipjiea^ as conceptacula externally identical with their peri- 

 thccia, do manifestly unite the O'idiums to the ErysipJies^ and they afford 

 the best evidence that both appertain to the same genus of plants. In 

 other words, the organs in question do not constitute, as M. Amici 

 would have it, the reproductive apparatus, ^ar excellence^ of the O'idiums^ 

 but they belong really to the Erysiphey as legitimately as the naked 

 spores of O'idium, and represent a mode of propagation which holds the 

 middle place, between these latter, and the thecigerous conceptacula. 

 It results, from this ascertained fact, that the ErysipJies, as well as 

 many other Fungi, possess at least three distinct modes, or three 

 special sets, of organs for reproduction. To take them in the order of 

 theii- successive development, the first and simplest is that which con- 

 sists in naked spores, arranged in'moniliform series, and which I have 

 denominated conidia: then come the conceptacula, of very various forms, 

 filled with innumerable and extremely minute granules, and which I call 

 pycnidiaj and finally, we see the most perfect globular and black seeds, 

 from the heart of which are engendered one or more oligosporous thecse 

 (see my " Auimadversiones " on ErysipJie, in the Berlin Botanische 



Zeitung, vol. xi, p. 257-267)- 



This beinff admitted, it is evident that the Oidiim Tuckeri, Berk., 

 with its naked acrogenous spores and its polysporous fruits, represents 

 an Erysiphe reduced to its two secondary modes of multiplication ; so 

 that the most important gap, which remains to be filled in the history 

 of this pest of our vineyards, will consist in deciding which species of 

 Erynphe supplies the deficiency. And till its ascophorous fruits shall 

 have been observed, its species cannot be satisfactorily ascertained; 

 for the two other kinds of propagation are insufficient to distinguish it 

 from many of its congeners, which are furnished with precisely the same 



* Whatever be the species ol Erysiphe to which we must refer that M infesU 

 the Vine, the absence of its ascophorous fruits is not a peculiar or unwonted cha- 



