4 HUMPHREY 
THE PARASITIC FUNGUS ASSOCIATED WITH FOSSOMBRONIA 
LONGISETA AUST. 
In the writer’s recent studies on the Development of /ossom- 
bronia longiseta* no reference was made to the structure of the 
infecting fungus; in fact, the material then in hand was too 
scanty to make anything like a satisfactory study. Since the 
publication of the above paper, however, excellent material has 
been found in various stages of development, and the relation of 
fungus to host has been clearly worked out. 
So far as could be ascertained, the host is invaded from with- 
out by hyphe that make their entrance through the rhizoids or 
directly through the cells of the host stem. The infection of 
the rhizoids is very similar to that described by Cavers’ for 
Lophozia, Cephalozia and other hepatice. As a rule the 
hyphez not only invade the rhizoids but extend throughout the 
tissues of the host, regardless of the nature of the substratum, 
thus differing somewhat from the nature of infection reported 
by Cavers where he has observed that the degree of infec- 
tion varies with the amount of humus in the soil. In F/os- 
sombronia, as a rule, the hyphe infecting rhizoids alone were 
confined to the inner wall of the organ, though in some instances 
not a few rhizoids were found in which hyphez had penetrated 
through the wall to the exterior as shown in Fig. 3. The host 
thus affected was growing in soil containing little humus and 
in no case were these external hyphe observed to grow longer 
than those figured. The hyphez confined to the rhizoids are 
very seldom branched and are rather remotely septate. In cer- 
tain parts, however, usually at the end of a branch, short seg- 
ments not unlike conidia develop and are abstricted from the 
hypha. The subsequent behavior of these has not been 
observed. It is, however, quite probable that these structures 
furnish one means of transfer of infection. I did not find in 
Frossombronia anything comparable with the conidia described 
by Jeffrey * as occurring in the endophyte of Botrychium vir- 
ginianum. 
1Humphrey, 1906: The Development of Possombronia longiseta Aust. Annals 
of Botany, Vol. XX, No. LXXVII. 
A oc: cit. 
2 170G; (Cit. 
