Butler . —On Allomyces , a new Aquatic Fungus . 1025 
are usually slightly constricted at the septum, except at the origin of 
a branch. 
The sporangia are formed in great abundance, either singly or in basi- 
petal chains, at the ends of the hyphae. They are ovoid or barrel-shaped 
cells measuring 40-70 by 30-40 p, with thin walls and granular hyaline 
contents. They are always inserted by a broad base on the ends of the 
fertile hyphae, from which they are cut off by a well-developed septum. 
Rarely, after a sporangium has formed at the end of a hypha and the axis 
has continued to grow from below it, a segment immediately beneath the 
origin of the branch becomes transformed into a sporangium. Fig. 1, a, 
shows such a case, the lowest sporangium having been formed after the 
upper was cut off and a new branch had arisen below it. Similarly, two 
sporangia may appear to arise side by side from the lowest of a chain so as 
to result in the production of a branched chain. In this case also the lowest 
is the last formed. By a repetition of subsporangial branching with early 
formation of new sporangia, rather complicated clusters of these organs 
may be formed, Fig. 6 showing one of the types met with. The contents 
of the mature sporangium are hyaline and granular. The papillae of 
discharge appear quite soon and are usually several in each sporangium. 
Fig. 7 shows a chain of ripe sporangia with the papillae formed and ready 
to burst. Usually there are two to four, less often only a single terminal 
one. They are large, very brightly refractive, and evidently formed of 
a protusion of the softened sporangial wall. They generally rupture 
simultaneously, or almost so, to emit the zoospores. 
The zoospores are formed before the rupture of the papillae, being 
visible as rounded masses tightly filling the sporangium. The papillae then 
dissolve without any trace of the formation of a vesicle such as occurs 
in other Leptomitaceae ( Rhipidium , Araiospora , Sapromyces). At first the 
zoospores pass out rapidly, though singly, separating immediately on exit. 
Later, as the crowd within becomes less dense, they emerge slowly, often 
with a more or less creeping movement. The last few left within the 
sporangium wander slowly, and with frequent amoeboid movements, around 
the walls and cavity, ultimately becoming engaged in one of the openings 
and creeping out. After exit, the zoospore lies near the sporangium for 
some time, up to five or ten minutes, and goes through a series of re¬ 
markable amoeboid changes. As it emerges it has usually the shape shown 
in the upper part of Fig. 10, a hyaline cap occupying the anterior end of 
the elongated body, and a single long and moderately stout cilium the 
posterior. The subsequent changes in shape are shown on the left-hand 
side in Fig. 10, drawn from a single spore. During these changes it is 
sometimes difficult to see the cilium, but it appears to be persistent. At 
the end of the amoeboid period the zoospore takes on the shape shown at 
the bottom of Fig. 10, and swims rapidly away. The swarming period 
