CHAPTER 1.—HISTOLOGICAL CHARACTERISTICS. 9 
The coloration of the membrane is accompanied with increased firmness and in 
most cases with exceptional power of resisting the action of concentrated sulphuric 
acid, phenomena which taken together recall the similar behaviour of the sclerosed, 
lignified, and suberised membranes of the higher plants. With the coloration therefore 
we may also speak of the sclerosis of the membranes. We learn also from other 
sources that the colouring at least is due to the interposition of substances which 
can be withdrawn by solvents from the membrane which then remains behind colour- 
less, as we can withdraw the colouring deposits from the sclerosed membranes of 
Pteridophytes, or lignin and suberin from lignified and suberised cell-walls. We 
cannot at the present day speak of lignification in the strict sense of the word 
in connection with the membranes of the Fungi, since they do not show Wiesner’s 
reactions when treated with anilin compounds and with phloroglucin. Phenomena 
approaching at least to suberisation in the strict sense of the word appear to occur 
sometimes, according to C. Richter’s observations on Daedalea quercina. The 
greater part of the Fungi have not been subjected to any close examination on these 
points ; the purely empirical expressions, coloration and sclerosis, may therefore serve 
for the present as general designations of the phenomena. 
But there is another kind of membrane in the Fungi which is distinguished from 
those hitherto described by its gelahnous or even mucilaginous nature. The mem- 
brane in the dry state is hard and cartilaginous and swells by absorption of water to 
several times its former volume in the dry state; its consistence therefore in the 
moistened vegetating state is that of a tough or soft jelly. The outer layers of many 
filamentous mycelia have this gelatinous constitution, which is very conspicuously 
seen when the plants are cultivated in a fluid. The hyphae, when examined by 
transmitted light, appear to have a delicately thin membrane which seems to be 
surrounded by a hyaline fluid; further examination discloses either a distinct 
gelatinous sheath round each hypha, or a diffuse gelatinous mass in which the 
branched hyphae are all imbedded. Zopf observed this in Fumago for example. The 
phenomena present themselves in a very beautiful form in the Sclerotinieae when 
cultivated in saccharine solutions. The membranes of Saccharomyces Cerevisiae must 
be of this nature according to the observations of Nageli and Léw. 
Soft gelatinous membranes also characterise in many cases large masses of tissue 
of definite shape, which appear at first sight to be slimy mucilaginous masses and 
may be designated gelatinous Issue (Gallertgewebe) or gelatinous felt (Gallertfilz). 
Beautiful examples of this formation may be seen among the larger mushrooms in 
the gelatinous bodies of the Tremellineae, in the gelatinous layers of the peridium 
of the Gasteromycetes, as Geaster hygrometricus, Melanogaster, Hysterangium, the 
Phalloideae, Mitremyces, &c. (see Division II), in Bulgaria and Cyttaria, in the greasy 
slimy superficial layers of the pileus in such Hymenomycetes as Amanita Muscaria, 
Agaricus Mycena of the section Glutinipedes, Boletus luteus, &c., and in the young 
mycelial strands of Agaricus melleus (section VII). Membranes of the viscid 
gelatinous type are found in the elements of most -Lichen-fungi, in those of the 
sclerotia of Sclerotinia and Typhula gyrans (section VIII), of the thallus of Hydnum 
erinaceus, of the massive sclerotium-like thallus of Polystigma and of the mycelium 
-of Hysterium macrosporum (Hartig). In the three last-named cases and in many 
Lichen-fungi (see also Division III) the gelatinous membrane-lamellae are coloured 
