PHYSIOLOGY AND MORPHOLOGY OF CALIFORNIA HEPATIC 9 
fact an extensive examination of plants of both sorts leads one 
to conclude that the presence of the fungus is of no advantage 
to the host and in many instances is an evident detriment. In 
March, 1906, while making some field studies upon /ossom- 
bronia, the writer observed that certain plants appeared to be 
dying. The affected plants were in some instances almost 
white, apparently from loss of chlorophyll. Closer examina- 
tion with a hand-lens revealed the presence of a great number 
of minute black bodies along the length of the stem and in the 
leaves. These were especially abundant near the base of the 
leaf. On further examination with the microscope it was found 
that these black bodies were sclerotia within the cells of the host 
and the development of these resulted ultimately in the death of 
the host. It was at first thought probable that this fungus was 
distinct from the one found invading the rhizoids and stem tissue, 
but a careful study seems to show that the two are identical. At 
least so far as concerns the host the development of these scler- 
otia marks the period of greatest activity of the fungus, and its 
truly parasitic nature is manifested. Up to the appearance of 
the sclerotia the life of the host is not seriously affected but as 
soon as the hyphe begin to extend and to form the structures 
that later develop sclerotia a very evident drain upon the vitality 
of the host sets in and increases with the further development 
of these structures. 
It was at first thought that these might be perithecia of some 
ascomycete but microtome sections demonstrated their true 
nature. Wherever they occur the cells containing them become 
considerably distended and completely filled. Their presence 
causes no abnormal development of the cell as regards thickness 
of wall or form, though the cell-contents become much modified 
to the extent that all vestige of any starch, oil, cytoplasm, etc., 
has disappeared, even the nucleus is absorbed and the entire 
cell cavity is filled by the sclerotium. 
The behavior of the hyphz with reference to the nucleus and 
chromatophores as described by Cavers' for the fungus infect- 
ing Monoclea does not occur in the case of the fungus under 
‘Cavers, 1904: Contributions to the Biology of the Hepatice. Part I. 
Targionia, Reboulia, Preissta, Monoclea, p. 39. 
