of the Genus Doassansia , Cornu . 23 
tonii , the most common species of pondweed in Eastern 
Connecticut. It has been looked for on several other species, 
but never detected, while it has been found on P. Claytonii in 
a number of localities. The fungus reaches its full develop- 
ment at about the time when the fruits of the pondweed are 
fully ripened. The affected ovaries may be told from the 
normal fruits of the same raceme by being swollen to from 
5 to 6 times the normal size and by being a dark olive-green, 
while the ripened fruits are more inclined to a yellowish brown. 
The leaves of infected plants have been examined in almost 
every case, but no sign of sori has been detected in them. 
The mycelium is not very abundant and possesses no 
characters particularly distinctive of the species. It is found 
in the neighbourhood of the sori and to some extent also in 
the peduncle of the raceme. It has not been looked for in 
other parts of the host, but probably occurs throughout the 
length of the stem at least. 
The topography of a cross-section of the ripe drupe-like 
fruit is somewhat as follows : the section itself is ovate ; the 
cross-section of the embryo is circular and is a little to one 
side of the centre towards the broader, rounded end of the 
section ; the section of the endocarp comes next, surrounding 
the embryo-cavity; it is also ovate, but the narrow pointed 
end is toward the broader end of the general section. When 
ripe the endocarp, or nutlet, is composed of thickened, 
sclerotic cells, but when young it consists of large, thin- 
walled, parenchymatous cells filled with starch. The epicarp 
is a soft layer, of about equal thickness in all parts of the 
section. It possesses conspicuous intercellular spaces, which 
are largest and loosest at the broad end of the section and on 
the sides. The epidermis forms the outermost layer of the 
epicarp. 
The sori are confined to the endocarp, and are formed 
among its cells in the greatest abundance, forcing them apart 
until the endocarp becomes several times as thick as it 
normally would be. The cells of the endocarp retain their 
thin walls and starchy contents, and never assume, when 
