34 
F. Cavers — 
In September, 1902, the writer received from Mr. G. Webster, 
of York, a large supply of living specimens of a New Zealand 
liverwort, Monoclea Forster /, which had been cultivated in a green¬ 
house. This plant has a broad creeping thallus, showing irregular 
dichotomous branching. In general habit the thallus resembles that 
of Pellia, but is broader and thicker. In every plant examined, 
vertical sections of the thallus showed a sharply defined mycorhizal 
zone, consisting of from two to four layers of cells densely filled 
with branching fungal hyphae. This zone is confined to the thicker 
median portion of the thallus and extends to within a short distance 
of the growing-point. In longitudinal sections of the thallus, the 
progress of the hyphae through the tissues can be followed step by 
step. As the hyphae pierce the cell-wall and branch out in the 
cell-cavity, the nucleus of the infected cell grows in size and often 
becomes enveloped by a tuft of short hyphal branches. All the 
cells of the thallus (excepting those which form rhizoids and certain 
scattered cells containing large oil-bodies) contain chloroplasts, and 
in some cases the latter become, like the nucleus, surrounded by 
tufts of short hyphae, in a manner strongly suggestive of the 
formation of a lichen. On some of the hyphae there are formed 
large spherical vesicles, many of which have thickened walls, as in 
Fegatella. 
Golenkin 1 has recently shown that an endotrophic mycorhiza 
exists in Marchantia pabnata, M. paleacea, Preissia commutata , 
Targionia hypophylla, and Plagiochasma elongatum, in addition to 
Fegatella conica. He states that in all cases the fungal hyphae are 
confined to the compact ventral tissue, and that the infected cells, 
though they retain their nuclei and protoplasm, never contain 
starch or chlorophyll. Golenkin compares the fungus with that 
found in the roots of Neottia and the prothallia of Lycopodium , and 
suggests that the function of the mycorhiza in the Marchantiaceae 
investigated by him is that of storing water and enabling the plant 
to resist drought. Against this view, however, it may be pointed 
out that (1) Fegatella and Monoclea, the forms which have been 
specially examined by the present writer and which have an 
exceptionally well developed mycorhiza, are typically hygrophilous 
plants, living on stones in streams and apparently not exposed in 
nature to the risk of becoming dried up ; (2) in the case of Fegatella 
the storage of water is well provided for by the highly developed 
mucilage-organs, strings of large mucilage-containing cells which 
traverse the midrib, in addition to numerous scattered mucilage 
1 Golenkin, Die Mycorkiza-iiknlichen Bildungen der Mar- 
cliantiaceeu, Flora, Band 90, 1902, p 209. 
