204 Ridler . — The Fungus present m 
Within twenty-four hours the spores were germinating vigorously, and 
cultures of the fungus were obtained. These were reinoculated on various 
media. 
Identification of the Fungus. 
The fungus isolated in this way is a species of Phoma. It has not 
been found possible to reinoculate with it, as no Pellia without the fungus 
has been found. Attempts were made to propagate the Pellia alone from 
the sterile apices of plants, but without success. Young gametophytes of 
Fig. 8. Schematized drawing of a longitudinal section through the thallus and sporogonium. 
Shaded portion indicates the infected region, x 15. c ., capsule ; pc., pycnidium ; el., elaterophore ; 
ct., calyptra ; z’., involucre; s., seta; /., foot; a., antheridium ; th., thallus; rh., rhizoid. 
i 
the liverwort have been placed under similar conditions, but did not develop 
to any extent. 
Physiological Relationships. 
The Gametophyte. The effect of the fungus on the tissue of the game- 
tophyte is well marked. When first infected the cells of the thallus possess 
numerous chloroplastids and well-marked protoplasmic contents. As infec- 
tion proceeds, the cells become brown and discoloured, and the chloro- 
plastids disappear from all but the two or three layers of cells nearest 
the upper epidermis, which are free from the fungus. In a well-infected 
thallus the lower part becomes absolutely brown ; the difference between 
this infected zone and the upper layers is, in some cases, very marked, the 
latter being still quite green and the contents of the cells uninjured. 
The fungus in the brown zone is obviously in a flourishing condition, 
as are also the swollen vesicles. The cell-walls of the liverwort are 
apparently quite uninjured by the fungus, except at the point of pene- 
tration. 
The presence of sphagnol in the cell-walls was tested for, but none 
was present. In this case there is therefore no evidence of an inhibitory 
influence exerted on the growth of the fungus, which may be the reason 
why it is able to obtain such a hold on the plant. 
The relationship between the fungus and the gametophyte may be 
one of symbiosis. The apparently constant occurrence of the fungus in the 
