VINE FUNGUS. 



[ 678 ] 



VINE FUNGUS. 



pearly shining bodies of oval form ; and the 

 application of sufficient power shows that 

 the horizontal filaments bear numerous erect 

 branches or pedicels, consisting of short- 

 jointed filaments (PL 20. fig. 8), the terminal 

 cells of which (or two last) are elliptical and 

 expanded. These terminal cells are soon 

 matured and then fall off"; vast numbers of 

 them are produced, and are found lying 

 upon the surface among the creeping fila- 

 ments, where they quickly germinate (PI. 20. 

 fig. 9), and produce new ramifications of 

 mycelium. The fungus, as thus described, 

 constitutes the Oidium proper, and the de- 

 ciduous terminal cells form the so-called 

 spores. But the history of the development 

 of the mildew^ does not cease here. 



In the first place, the detached ^ spores ' 

 do not always produce a filament as repre- 

 sented in fig. 9; some of them present, 

 while still attached, a kind of segmentation 

 of the protoplasmic contents (fig. 10), and 

 detached examples are found filled with 

 minute ' sporules ' of elongated elliptical 

 form. These minute ' sporules ' are either 

 discharged by a dehiscence of the ' spore ' 

 (fig. 11), and then germinate, or sometimes 

 they germinate in situ, and send out slender 

 filaments through the walls of the spore. 

 We have found also that the large filaments 

 produced by the simple large ' spore ' (fig. 9), 

 do not always at once form a regular myce- 

 lium, but give rise to slender pedicels, ter- 

 minating in a point bearing minute solitary 

 corpuscles of about the size and form of the 

 ' sporules ' above described, and resembling 

 the spermatia of many of the higher Fungi. 



In addition to this, we have sometimes 

 observed those ' spores ' which ])roduce the 

 ' sporules ' in their interior, with their outer 

 membrane finely punctate, and in very rare 

 cases, this form of fruit was composed, not 

 of a single terminal cell, but presented indi- 

 cations of cross septa, as if two or more cells 

 of the summit of the pedicel were confluent 

 into one sac; here the punctation of the 

 surface was very strongly marked. 



Thus far we depend u])on our own obser- 

 vations, but Mohl, Tulasne and others de- 

 scribe a still more highly developed fruit 

 than that last noticed ; they have found the 

 terminal body, producing ' sporules,' with a 

 distinct cellular coat (PI. 20. fig. 12), from 

 which the sporules are discharged by a ter- 

 minal dehiscence. Mohl found this body, 

 very rarely, of spherical form. We have 

 never seen this cellular coat; in the cases 

 we have met with, the coat was certainly 



only punctate or tubercular; probably the 

 structure was not mature, nevertheless the 

 ' sporules ' were distinctly evident. 



These phaenomena, exhibited by the Vine 

 fungus, clearly agree with those exhibited 

 by the Oidia always accompanying certain 

 Erysiphe*, as described under that article ; 

 and most of the authors who have written 

 on this subject, therefore conclude that the 

 Vine fungus is really an Erysiphe, of which 

 the perfect, ascophorous fruit has not yet 

 been discovered. A comparison of the 

 figures marked 12 (PI. 20), from the Vine, 

 copied from Mohl, with those of the Hop 

 Erysiphe under fig. 14, will show the agree- 

 ment of structure between the two plants. 



It remains only to add a few remarks as 

 to the interpretation or nomenclature of the 

 diff'erent organs. Mohl, Tulasne, &c. have 

 denominated the simple ' spores ' above de- 

 scribed (figs. 8, 9) conidia ; but as we have 

 stated, the cells are convertible into what 

 may be called sporanges, producing ' spo- 

 rules ' (or true spores) without alteration of 

 structure. When their walls become cellu- 

 lar (fig. 12), the sporangial character is more 

 decided; but as the Erysiphes produce a 

 more perfect sporange, in which asci are 

 developed, the name of pycnidia is applied 

 to them. This fruit it was which gave rise 

 to the establishment of a supposed distinct 

 genus, by Cesati, under the name of Ampe- 

 lomyces ; while Ehrenberg, also regarding it 

 as a distinct plant, made it the type of a 

 genus called Cicinobolus, on account of the 

 peculiar tendril-like extrusion of the ' spo- 

 rules' (fig. 12 s). Mohl distinguishes it as 

 the Cicinobolus-fruit, which he, like Tulasne, 

 finds constantly associated with other (un- 

 doubted) Erysiphes (fig. 14), in very slightly 

 diff'erent and equally irregular forms. 



There can be no doubt whatever in the 

 minds of those who have watched the deve- 

 lopment and progress of the Vine Fimgus, 

 that it is the cause and not a consequence of 

 the ' murrain ; ' still there are various curious 

 circumstances connected with it not at all 

 understood ; it is probable that peculiar at- 

 mospheric conditions induce predisposing 

 states of the plants; but the phaiuomena 

 are enigmatical; we have had it completely 

 covering a vine in a small greenhouse, de- 

 stroying all the fruit one year ; and although 

 no precautions were taken (as it was desired 

 to study the disease), no sign of mildew ap- 

 peared there the next year; while on an 

 out-door trellis, a few yards off", the disease 

 reappeared in a slight form in the second 



