CHAPTER I. — 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 can be withdrawn by solvents from the membrane which then remains behind colour- 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 gelatinous 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 Low. 



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 tissue (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 lyiuscaria, <i™ 

 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 

 Z> fcrinaceus, 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 



