PHYSIOLOGY AND MORPHOLOGY OF CALIFORNIA HEPATICH II 
others yet free from the fungus, but it is owing to the fact that 
the degree of infection is but slight and the vigor of the host 
is sufficient to throw off for a time the harmful effects of the 
parasite just as the leaves of cultivated lettuce maintain apparent 
full vigor during early stages of the infection by Bvremza 
lactuca.' 
Experiments designed to ascertain the effect of the fungus 
upon very young plants of either Hossombronza or Fimbriaria 
have thus far failed, and it cannot be decisively stated here that 
Fimbrvaria is at all susceptible to infection by this fungus. The 
examination of a large number of plants of all stages of develop- 
ment has shown our common species, /. californica, compara- 
tively free from infection by any fungus. Recently, however, 
the author has found a few plants of this species attacked by a 
fungus which seems, in material thus far examined, to be con- 
fined entirely to the cells of the first four layers on the ventral 
side of the thallus. Hyphe in considerable numbers were ob- 
served in both the smooth and tuberculate rhizoids. These 
showed but slight tendency toward branching, in many instances 
extending the entire length of a rhizoid without producing a 
branch. The hyphe confined to the rhizoids, compared with 
those within the mycorrhizal zone of the thallus, are very much 
more delicate; but upon extending into the cells of the thallus 
they branch profusely and develop relatively thick and tough 
walls. The fungus resembles the one described above for /os- 
somoronza, in that it is filamentous and septate. Structures com- 
parable to vesicles, conidia or sclerotia have not yet been 
observed. The presence of the fungus seems in no wise to re- 
tard the growth or affect the vigor of the thallus and no plants 
have yet been found in which the hyphe have penetrated the 
chlorophyll-bearing tissue. 
THE PARASITIC FUNGUS ASSOCIATED WITH ANEURA 
MULTIFIDA MAJOR. 
While in the field collecting Aneura the writer observed that 
a considerable number of plants had taken on a rusty brown 
‘An illuminating discussion of symbiosis and parasitism is to be found in 
Plant Physiology. Peirce. Pp. 85-92 inclusive. 
