20 6 
Ridler . — The Fungus present in 
The fungus also occurs in proximity to the antheridia and archegonia. 
2. In some cases the fungus is present in the cells of the sporophyte, 
where it may infect the whole of the tissues, sometimes rendering them 
abortive. 
3. The fungus has been isolated from the sporophyte, and identified 
as a species of Phoma . 
4. The effect of the fungus on the gametophyte of Pellia is very 
marked. The protoplasmic contents of the infected cells are killed, the 
chloroplastids disappear, and the cells ultimately become brown in colour. 
The relationship existing between the fungus and the liverwort may 
be a symbiotic one; but the Phoma is probably the dominant partner 
and of little use to the Pellia — in extreme cases killing the latter, though 
usually it is able to grow and reproduce in the normal manner. 
5. The effect of the fungus on the sporophyte is twofold. The contents 
of the cells are killed, and the cell-walls are also wholly or partially 
absorbed. 
The relationship existing in this case is not symbiosis. The fungus 
causes a disease, killing the tissues of the sporogonium and in some cases 
rendering them abortive. 
The courtesy of Professors Massart, Priestley, and Small, in providing 
material for this work, has been of great value in proving that the presence 
of the fungus in Pellia epiphylla is not restricted to a limited locality, 
but that it is normally present in plants obtained from such different 
sources. 
I wish to express my sincere thanks to Mr. C. Hunter, who suggested 
the subject of this paper, and whose constant valuable help and advice 
alone have made it possible to carry out this investigation. 
I also wish to thank Professor O. V. Darbishire for his advice and 
interest in this work. 
Cryptogamic Research Laboratory, 
University of Bristol. 
November 1921. 
References. 
1 . Beauverie, J. : Etude d’une Hepatique a thalle habitd par un champignon filamenteux. 
Comptes rendus de l’Acad. des Sci. de Paris, 1902, p. 616. 
2 . Britton, E. G. : Fungi on Mosses. Bryologist, 1911, vol. xiv, p. 103. 
3 . Cavers, F. : On Saprophytism and Mycorhiza in Hepaticae. New Phytologist, 1903, vol. ii, 
p. 30. 
