368 Bancroft.—Researches on the 
to Cladosporium and the same change occurs in an artificial medium, 
Hormodendron is considered to require a living matrix for its further 
continuance. 
The occurrence of Cladosporium on dead leaves, its production in 
an artificial, cultural medium, and its tendency to reproduce itself in such 
a medium show that it is to be regarded as a saprophytic form. In the 
life-history of many fungi when two forms are concerned, the one a parasite 
and the other a saprophyte, it is customary for the saprophytic form to 
be ultimately produced in an artificial medium and to continue to reproduce 
itself in such a medium. In the genus Ustilago , for example, the secondary 
spores produced by the so-called Ustilago- spores continue to reproduce 
themselves in an artificial medium, and it is only when they are transferred 
to the host-plant that they give rise to the parasitic form from which the 
Ustilago- spores are again produced. 
Conidia of Cladosporium , when germinated at a temperature of 6o° F. 
or above, give rise to conidia of Hormodendron. This is considered as 
a means by which Hormodendron is produced for the purpose of infecting 
living leaves during the summer; there are, then, two sources from which 
Hormodendron is derived during the summer, namely, conidia of Clado- 
sporium and conidia of Hormodendron. A lower temperature has been 
shown to suppress the production of conidia of Hormodendron and to favour 
the formation of conidia of Cladosporium. This points to Hormodendron 
being a summer form and to Cladosporium being a later form. 
The fully formed microsclerotia have been shown to produce conidio- 
phores which bear conidia of Cladosporium , and these conidia of Clado¬ 
sporium have been shown to give rise to conidia of Hormodendron after 
germination. This is considered to afford the means by which Hormo¬ 
dendron is regenerated in the spring of each year. The microsclerotia are 
formed in late autumn, after the conidiophores of Cladosporium have 
disappeared, and exist through the winter in a state of inactivity. On the 
recurrence of spring they germinate to give rise to conidia of Cladosporium } 
from which conidia of Hormodendron are produced, and so can infect the 
living leaves of plants during the summer. 
From the experimental results and from the conclusions based on 
them, the life-history of Cladosporium herbartim is considered to include 
two conidial forms, the one a parasitic form, Hormodendron , and the other, 
Cladosporium , a saprophytic form. The latter form is capable of existing 
in an inactive condition through the winter. Such a life-history, which 
is made up of two conidial forms only, is unusual among the Fungi. Each 
form has been shown to be capable of giving rise to the other, and an 
attempt has been made to elaborate the conditions under which one form 
tends to pass into the other. The life-cycle appears to be complete, and 
the intervention of any other spore-form would be unnecessary. 
