380 DIVISION III.—MODE OF LIFE OF THE FUNGI. 
afterwards by Brefeld’. Species of Mucor (M. stolonifer and M. racemosus), Penicillium 
glaucum, Trichothecium roseum, and other species are able to make their way into sound 
juicy fruits, and vegetate and cause rottenness in them. These do not rot without the 
Fungi. If spores are sown on the uninjured surface of thick-skinned fruits like the 
apple and pear, where there is sufficient moisture for germination, the germ-tubes are 
unable to penetrate into them or do so with difficulty ; but they enter with ease if the 
spores are sprinkled on wounded places where the skin is broken. Mycelia which have 
already acquired some strength are better able to force their way through the unbroken 
skin. The softer the fruits have become from other causes the more easily are they 
penetrated by the Fungus ; fruits therefore like strawberries and raspberries with thin 
skins are very liable to be attacked. Davaine found that the vegetative organs of 
succulent plants, such as Sempervivum, Mesembryanthemum, and Stapelia show the 
same phenomena as thick-skinned fruits. Observation of the fruits shows that the 
Fungi develope more easily the nearer the vital powers of the parts attacked are to 
their lower limit, and at this point the conditions of saprophytic vegetation make 
their appearance. 
The parasitic phase of vegetative life is seen in its more characteristic form in 
many other facultative parasites on plants, and with many shades of difference in 
different species. The Sclerotinieae, Pythieae, Nectrieae, and Hartig’s tree- 
destroying Hymenomycetes may be taken as examples for closer consideration. 
Many other Fungi, species of Pleospora and Cladosporium for example and allied 
forms will have to be added to this if the group is more thoroughly investigated. 
Of the Sclerotinieae, Sclerotinia Sclerotiorum (see pages 30, 52, 218) may go 
through the whole course of its development as a saprophyte and finds opportunity 
for this in the natural state on dead plants. But it can also attack certain living and 
healthy plants and parts of plants as a parasite and destroy them. But according to 
our present experience it always requires to go through a previous stage of existence 
as a saprohyte in order to be capable of parasitism. The allied 8. ciborioides which 
preys on clover behaves in a similar manner. 
Sclerotinia Fuckeliana inclines more in the direction of saprophytism; both 
the mycelia which produce gonidia and those which form sclerotia are found chiefly in 
dead parts of plants, especially on decaying leaves, &c. At the same time it is one of 
the chief agents in the production of decay in juicy fruits, and more thorough investi- 
gation will confirm the experience drawn from every conservatory, that the mycelium 
when it has once reached a certain degree of strength becomes parasitic on living plants 
and kills them. 
I have previously? given a very imperfect account of the circumstances connected 
with the vegetation of Peziza Sclerotiorum, and at that time I also misunderstood to 
some extent the facts which were stated about it. More recent observations have given 
me a clearer understanding of the matter and it will be well to describe them here in 
greater detail. The ripe ascospores germinate in pure water, emitting short tubes which 
soon cease from further development ; in a suitable nutrient solution, in must of grapes for 
instance and onripe juicy berries of any kind, they develope into a vigorous mycelium 
which forms sclerotia, and the same result is obtained if they are sown on dead vegetable 

1 Sitzgber. d. Naturf. Freunde zu Berlin, Dec. 21, 1875. See Bot. Ztg. 1876, p. 281. 
? See the first Edition of this work, p. 215. 
