VINE-FUNGUS. 



[ 809 ] 



VINE-FUNGUS. 



face from the influence of the air, since 

 when young berries are invaded, the inter- 

 nal development proceeds, and the sphace- 

 lated epidermis preventing the natural ex- 

 pansion, the grapes burst and rot. In this 

 case, species of Botrytis, &c. appear upon 

 the decomposing pulp, as on all similar sub- 

 stances ; and these must be distinguished 

 from the proper mildew. When full-grown 

 leaves are affected to a moderate extent, 

 the vitality is often only partially affected, 

 causing a laxity of the tissue, and more or 

 less fading of the green colour, without 

 inevitable decay. 



When the mildew is observed with a low 

 magnifier, its surface exhibits a mealy ap- 

 pearance, arising from minute bead-like or 

 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 (PI. 26. fig. 8), the 

 terminal cells of which (or the last two) 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 filaments, where they quickly ger- 

 minate (PI. 26. fig. 9) and produce new 

 ramifications of mycelium. The fungus, as 

 thus described, constitutes the Oidium pro- 

 per ; and the deciduous 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 l 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 f 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 sometimes give rise to slender 

 pedicels, terminating 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 produce the 



' sporules ' in their interior, with their outer 

 membrane finely punctate ; and in very rare 

 cases this form of fruit was not composed 

 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 con- 

 fluent into one sac ; here the punctuation 

 of the surface was very strongly marked. 



Thus far we depend upon 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 bodv> producing l sporules/ with a 

 distinct cellular coat (PI. 26. 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 j 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 phenomena, exhibited by the Vine- 

 fungus, clearly agree with those exhibited 

 by the Oidia always accompanying certain 

 ERYSTPH<E, as described under that article ; 

 and therefore most of the authors who have 

 written on this subject conclude that the 

 Vine-fungus is really an Erysiphe, of which 

 the perfect, ascophorous fruit has not yet 

 been discovered. A comparison of figure 

 12, PI. 26, from the Vine-, copied from 

 Mohl, with those of the Ho^-Erysiphe, fig. 

 14, will show the agreement of structure 

 between the two plants. 



It remains only to add a few remarks as 

 to the interpretation or nomenclature of the 

 different 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 cel- 

 lular (fig. 12), the sporangia! character is 

 more decided ; but as the Erysiphce 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 l spo- 

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

 the Cicinobolw-faiiit, which he, like Tulasne, 

 finds constantly associated with other (un- 



