PHYSIOLOGY AND MORPHOLOGY OF CALIFORNIA HEPATICvE 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 I^ossotn- 

 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 hyphae 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 an}' 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 hypha; with reference to the nucleus and 

 chromatophores as described by Cavers ^ for the fungus infect- 

 ing Monoclca does not occur in the case of the fungus under 



^Cavers, 1904: Contributions to the Biology of the Hepaticse. Part i. 

 Targionia, Reboulia, Preissia, Mo7toclea, p. 39. 



