1024 Butler.—On Allomyces, a new Aquatic Fungus. 
fertile branches arise, which bear the reproductive organs, sporangia and 
resting spores. From the basal cell numerous fine branched rhizoids 
penetrate the substratum. The most striking character of the plant, in 
view of its being an undoubted Phycomycete, is that it is distinctly multi¬ 
cellular, all parts, except the rhizoids, being regularly septate. 
The various parts may now be described in detail. 
The basal portion is anchored to the substratum by a branching 
system of rhizoids arising from the lowermost cell. The lowest cell itself 
is variable in shape, sometimes almost square, sometimes oblong or clavate 
(Figs. 1-3). It measures from 100 to 200 /x in length by 60-100/4 in 
breadth, and is thick-walled, but not rigid. Above, it is either continued 
into a short column of three or four similar cells (Fig. 3), or branches 
dichotomously to form a fan-shaped body of large cells (Fig. 2). These 
again branch upwards, the succeeding branches being more slender and the 
tendency to dichotomy being usually lost. Frequently, whorls of three 
branches arise from the uppermost of the basal cells, but there is no 
regularity about this; dichotomy may be preserved for some time or the 
branches may arise at different levels from near the end of the basal cells. 
Each branch is cut off by a septum at the point of origin, and after the 
mass of basal cells is left, any branch may terminate in a sporangium, 
growth being usually renewed just below the sporangium, and the latter 
being then pushed a little to one side. 
The fertile branches radiate from the basal cells and are composed 
of septate hyphae, the cells reaching an extreme length of 250/4, with 
a breadth of 15-25/4. Usually a terminal sporangium is formed before 
growth has proceeded very far, and the axis is continued by a branch arising 
just below the sporangium, somewhat as in Phytophthora vexans. This 
may be repeated many times, each fertile axis thus forming a sympodium, 
as in Fig. 5; or branching of a more or less dichotomous type may occur, 
as in Fig. 4. In this case, as probably in all other cases of the sort 
amongst the Fungi, one of the branches arises a little behind the apex of 
the filament, apparent equality of origin being only subsequently reached. 
Ultimately the apex of every branch ends in a sporangium or chain of 
sporangia or a resting spore. The walls of the fertile branches are thin. 
The septa are formed regularly behind the growing apex, but secondary 
septation may occur at a later stage. Usually one develops at or near the 
origin of each branch. Sometimes they occur at more or less regular 
intervals throughout the axis, sometimes several are formed close together 
below a sporangium (Fig. 1). They appear to be laid down in interrupted 
plates from the periphery of the tube (Fig. 1 y y c). Usually they are com¬ 
plete, but rarely a small pore appears to be left in the centre, as in some, at 
least, of the higher Fungi. In no case observed was the septum reduced 
to a mere annular thickening, such as occurs in Gonapodya . The segments 
