408 DIVISION IIL—MODE OF LIFE OF THE FUNGI. 
membranes of the rind of Cetraria islandica, except those of the superficial coloured cells, 
turn a beautiful blue with solution of iodine alone, as Schleiden' has observed, 
owing to the presence of Dragendorff’s Lichen-starch in the cells (see page 10). 
The membranes of the medulla of Sphaerophoron coralloides show the same colour 
with iodine; Schwendener found that the rind of Cornicularia tristis and of some other 
species not precisely determined became blue with iodine only here and there. 
The membranes of the rind, especially the superficial layers, in many Lichens are of 
different hues owing to the presence of a colouring matter uniformly diffused through 
the substance of the rind, as in Cetraria islandica, Bryopogon jubatus and many others ; 
the dark colour of the under rind of Evernia furfuracea comes from the colouring of the 
outer lamellae of the membranes ; the narrow lumina are seen in section surrounded 
by thick colourless membranes, between which are dark brown bands forming boundary 
lines; the matters imparting this ‘uniform colouring have not yet been thoroughly 
investigated, at least not microchemically. 
Asecond series of colourings is caused by granular imbeddings or incrustations. The 
tissue of very many Lichens is seen to contain small round or elongated granules of some 
organic substance lying partly on the free surface and on the medullary hyphae, partly 
imbedded in the membranes which are united together without interstices. Granules of 
this kind, which are either colourless or only of a faint yellow colour even in the mass, 
occur for instance in the upper rind of Placodium cartilagineum and other species, in 
Imbricaria caperata, Dill., I. incurva, P. and other species, on the medullary hyphae of 
Peltigera, Solorina saccata and some species of Sticta (Schwendener), on the rind of 
Roccella, especially R.fuciformis and of Thamnolia and in the inner rind of Sphaerophoron 
coralloides ; distinctly or intensely yellow granules are found outside the rind of Evernia 
vulpina and Physcia parietina, ot imbedded in the peripheral region of the rind of 
Cetraria straminea (Schw.) and Usnea barbata and in the whole of the membranes of the 
rind of Psoroma gypsaceum, or scattered in groups through the rind of Bryopogon diver- 
gens (Ach.) and B. sarmentosus and especially of B. ochroleucus where they form an 
uninterrupted layer near the surface, and in the medullary hyphae of Sticta aurata 
and S. crocata and some other species ; red incrustations are found on the medullary 
hyphae of Solorina crocea. The presence of these bodies in the substance of the thallus 
and on it causes either a lively coloration, or, as in Thamnolia and Roccella, a dull yellow 
aspect and opaqueness in the parts in which they are found. They are all readily 
soluble in alkali either without change or with loss of colour, or at least deliquesce and 
become turbid under the influence of these agents, as in Physcia parietina and Solorina 
crocea, in the latter also without change of colour. It was not improbable therefore 
that the granules consisted of chinic acid, and Fr. Schwarz has recently proved that 
this is the case in a number of species. 
Another series of infiltrations and imbeddings is composed of inorganic matter. 
First and foremost is the rust-colour not unfrequently assumed by individuals (‘formae 
oxydatae’) of many crustaceous Licliens which are typically of another colour ; it has 
often been stated and has now been proved by Giimbel, that this colour is due to the 
infiltration of a salt of iron, perhaps of a vegetable acid. Still more remarkable 
is the occurrence of calcium oxalate in many Lichens especially of the crustaceous 
division, either in the form of octahedral crystals, or of irregular crystalline bodies, or of 
small granules. In accordance with the rule which prevails in the rest of the Fungi it 
is never found inside the cells, but either on the surface of the rind, or on the medullary 
hyphae or in the interstices between them, or imbedded in the shape of minute granules 
in the membranes of the compact tissue of the rind. The latter is the case for instance 
in Psoroma lentigerum, in which the entire rind is wholly opaque and white in reflected 
light, owing to the close array of granules of the salt. Besides the above species, in 
which the medullary hyphae are also incrusted with granules, they occur also in Ochro- 

' Grundzüge, II. 
