87 
THE ORGANIZATION OF CCENOGONIUM AND THE 
THEORY OF LICHENS. 
By M. le Dr. J. Muller, Professor in the University of 
Geneva.* 
( Translated by W. Phillips, F.L.S.) 
The genus Coenogonium , established in the Class Lichenes in 1820, 
by Ehrenberg, comprises at the present time about twenty species 
which grow in the warm regions of the two hemispheres. Their 
fruit, or apothecia, and their spores, approach those of the section 
Biatorina of the genus Patellaria, while their thallus, or vegeta- 
tive part, has a totally different structure, which approaches the 
genus Graphis. 
If of this thallus we examine the constituent elements — which 
are filiform, slightly branched, more or less parallel with each other, 
very loosely united in a felted mass, and which, according to the 
species, may take the form of a little bed, or of a flattened cushion, 
or may develop horizontally in the form of a fan, about 2 to 8 c.m. 
in diameter — we are struck with the great resemblance these fila- 
mentous elements present to the filaments of Conferva. Some of 
the large tubes (filaments), about 5-30^u (/z = y-oVw mm *)> accord- 
ing to the species, contain a single series of green cells, filled with 
chlorophyll, which touch end to end, and which are ordinarily 
several times longer than broad. But there the details cease if 
we study them with an ordinary microscope, and it is thus far 
that Ehrenberg defined the analysis of his new genus. 
By a superior analytical method, and by the aid of superior ob- 
jectives, Dr. Karsten and Professor Schwendener recognised in 
1862 that around some large confervoid filaments there exist other 
filaments much more slender, having a diameter of about l-2^u, 
which appear to be hyaline, and which creep in some measure on 
the surface of the large green filaments. There is but one single 
series around the green filaments, and yet this series is inter- 
rupted, the slender filaments not touching laterally in a regular 
manner ; but they often show some anastomosing and there occasion- 
ally form, at least in places, a rather close net-work. Hence we had 
two constituent elements in the thallus of Coenogonium as in other 
Lichens, that of the large green cells still enclosed in their mother 
cells, corresponding to the gonidia, and those of the slender hyaline 
filaments corresponding to the hyphal filaments. But a genitic 
correlation between the two had not yet been observed in 1866 (de 
Bary, “ Morphol. et Physiol, der Pilze und Flechten,” p. 270). 
It is clear, then, that according to the celebrated theory of Pro- 
fessor Schwendener, announced in 1867, the large green filaments 
will represent the nourishing Alga, and the slender hyphal filaments 
will be the parasitic Fungus, the two forming together the thallus 
* Communicated to the Physical and Natural History Society of Geneva 
Sept. 1st, 1881. 
