122 
Certain Fungi Parasitic on Plants. 
form from that of 3. The branched state of 4 illustrates the 
changes which take place in 2. I have observed many spores 
germinating like 3, upon the functions of which I have been 
unable to decide. After exposure for a few days, more new forms 
of fungi appeared on the branches of the mycelium of the Oidium. 
(See 5 and its ramifications, group B.) Nos. 6 and 7 next 
appeared, followed by 8 and 9 ; 10 represents a highly magnified 
spore of Penicillium glaucum, 9 ; 11, the spores of 7 germi- 
nating, which resemble Penicillium Armeniacum, Berk. The 
flask-shaped spores, 8 ( Antennaria tenuis, Ness.), are generally the 
last to appear. They belong to a genus of Torulacei, remarkable 
for their close resemblance to a Florence flask.* 
My object was to ascertain what changes, if any, would take 
place during the germination of the spores. I therefore varied my 
experiments in numerous ways, and am satisfied that the forms 6, 
7, 8, and 9 have no relation to the Oidium under experiment, but 
are distinct fermenting plants, living on and consuming the myce- 
lium and spores of the Oidium, preventing the further healthy 
growth of the vine fungus. The facts observed have an important 
bearing on the cultivation of foreign grape-vines when grown in 
moist hot-houses ; for since it has been shown that parasitic fungi 
are nourished by the spores and mycelium of the Oidium of the 
vine, and grow profusely on them, the vine itself will become 
affected by the growth of the fungi over its leaves, green branches, 
and fruit. I have frequently transferred to varnished glass slides 
the same class of spores direct from a leaf which had been kept 
unusually moist while growing. These will doubtless hasten the 
death of the plant on which they grow. The evidence is conclusive 
that when the flowers of sulphur have been applied early to mil- 
dewed vines, they have been saved, and that later applications have 
been unavailing. This may arise from the fact that the other forms 
of fungi, such as I have pointed out, may assist in the destructive 
work. These experiments have been repeated often under varied 
conditions, with an unvarying similarity of results. A slip of glass 
was varnished, and, when nearly dry, a vine-leaf covered with the 
Oidium was pressed on it, so that many of the spores adhered to 
the varnish. When the slip was introduced into a moist jar at the 
temperature mentioned, the spores adhering to the varnish germi- 
nated, as shown at B. When placed in an atmosphere containing 
turpentine, benzine, or carbolic acid, they failed to germinate, and 
the distorted forms of the Oidium were clearly seen, showing the 
destructive action of these substances on fungus germs. 
I next placed the dust of roll sulphur on Oidium spores, and 
* The 1 Micrographic Dictionary ’ says of this genus that “ no British repre- 
sentatives of this genus appear to have been recorded hitherto ” (p. 29, vol. i., 
second edition, I860). 
