RHIZOPHIDIUM POLYSIPHONIAE IN THE 
UNITED STATES 
CONTRIBUTIONS FROM THE HULL BOTAN ICAL LABORATORY 292 
GEORGE W. MARTIN 
(WITH TEN FIGURES) 
The morphology and distribution of the fungi parasitizing 
marine plants are still so imperfectly known that additional facts 
concerning any of them seem worth placing on record. Among 
some algal material collected by Dr. T. C. NEtson in Barnegat 
Bay, New Jersey, and sent by him to the writer preserved in 
formalin, occurred a small sterile plant of Callithamnion which 
was observed to bear numerous sporangia of a chytridiaceous 
fungus. The mature sporangia were globose or nearly so, from 
22 to 39m in diameter, averaging 33 u, and closely appressed 
to the attacked host cell, which could be sharply distinguished 
from the neighboring unattacked cells by the partial or nearly 
complete exhaustion and decoloration of its contents. In only 
one instance was more than one sporangium attached to a single 
host cell (fig. 8). The cell contents are destroyed first at the end 
at which the fungus is attached (fig. 3), and by the time the sporan- 
gium becomes mature the contents of the parasitized cell are, as 
a rule, almost exhausted (figs. 1, 2, 6, 8). In some cases a 
branched, rootlike mycelium, rather coarse for this genus, could 
be seen within the host cell and traced to the base of the sporan- 
gium (figs. 1, 2, 8, 9, 10). More frequently the mycelium could 
not be distinguished. The zoospores are from 2 to 3 u in diameter, 
globose or somewhat irregular in shape, and are evidently liberated 
through an opening developed from a papilla, of which each 
sporangium bears from one to several (figs. 1, 4, 5). Each zoo- 
spore contains a nucleus or oil globule, and in addition a much 
smaller body, observed only in the spores remaining in a nearly 
Botanical Gazette, vol. 73] [236 
