I2 HUMPHREY 
color. Upon careful examination it was found that they were 
in a dying condition owing to the presence of a fungus. A 
large quantity of material consisting of plants in a normal con- 
dition as well as those visibly affected by the fungus were 
brought into the laboratory in September, 1906, where the rela- 
tion of fungus to host could be more carefully studied. This 
species of Aneura is found growing on moist surfaces of rocks 
along streams, on decaying logs and moist banks of soil in 
which there is considerable clay. Material collected from all 
three of these sources contained a large number of infected 
plants so it 1s hardly probable that the fungus is one confined 
to plants growing on decaying wood. 
Aneura muliiida major, as well as other species of this genus, 
under certain conditions produce two-celled gemme in great 
numbers. It was found that many of these after a short time 
had germinated and some were infected. Figure 15 shows a 
young plant resulting from the germination of a gemma, into the 
older cells of which a fungus had penetrated by well-marked 
haustoria. ‘The diseased cells contained less chlorophyll and 
showed unmistakable evidences of the harmful effect of the 
fungus. Young plants of varying age and size were found to 
be infected. It was first thought likely that infection took place 
directly while the gemma was still within its mother cell, but a 
very careful examination of gemme failed to support any such 
view. It seems that young plants of less than four cells are 
rarely infected. The fungus develops conidia freely and it is 
probable that infection is brought about by their germination. 
A small number of young plants developing from germinating 
spores were observed, but as yet none of these has shown the 
presence of a fungus. 
In the older plants, hyphe from within the cells of the thallus 
grow downward extending into the rhizoids, though this is by 
no means so common as in the case of Fossombronza or Fim- 
briarta. Many rhizoids whether infected or not present a 
strong tendency to branch as shown in Fig. 16, aand 6. This 
is undoubtedly due to the influence of contact stimulus; in fact, 
rhizoids not in contact with the substratum are all quite simple 
and more delicate. 
