142 DIVISION II—COURSE OF DEVELOPMENT OF FUNGI. 
are several oospheres present the tubes often grow from one to another, and even 
form branches which grow up to and past different oospheres, and sometimes even 
pierce through the wall of the oogonium and pass outside it; but they always remain 

FIG. 69. A—C. Achlya racemosa, Hildebr. 4 end of a 
fertile branch with an empty sporangium at s surmounted by 
a head of gonidia out of which most of the spores have already 
swarmed away. Beneath it on short lateral branches are 
three oogonia with antheridial branchlets ; 2 before the deli- 
mitation of the oogonium and antheridia; 4 and c in the same 
stage as 8; both oogonia have two antheridia, and 2 has six, 
c seven ph B jum with two oosph and an 
antheridium resting on it; a fertilisation-tube from the an- 
theridium has reached the surface of the nearest oosphere. 
Caripe oospore. D—E. Achlya polyandra. Danoogonium 
with three germinating oospores about five weeks after 
maturity. The short germ-tubes of two of the oospores are 
protruding from the oogonium, the third lies bent inside it. 
The oogonii ins also two oosp which have not 
yet germinated, one of which is shown in the figure. Ea 
germinating oospore which has formed a small sporangium 
with a head of spores, 4 magn. 145, B and C 375, D and 
E 225 times. 


closed.and die in the course of ı-2 days 
while the oospheres are maturing. The 
short tubes of Aphanomyces scaber are the 
only ones Which I have examined which 
never showed this luxuriance of growth; 
they apply their apex firmly to the oosphere 
which in this species is solitary, and re- 
main in that position without change till 
the oospheres ripen in 2-3 days’ time. 
These facts show that the antheridia and 
fertilisation -tubes of the Saprolegnieae 
must be considered to be homologous with 
those of Pythium and that they may be 
called by the same name: but there is no 
ground for regarding them as really fer- 
tilising organs; for while in some species, 
as Achlya polyandra and Saprolegnia 
monoica, their mode of formation is always 
such as has just been described, there are 
other species in which the same plant may 
have these antheridia with their fertilisa- 
tion-tubes and at the same time antheridia 
without tubes, or oogonia without any an- 
theridia (Aphanomyces scaber, Saprolegnia 
hypogyna); and lastly there are species 
or races, extremely like those named above 
in other respects, which very seldom or never 
form antheridia. In all these cases the 
formation of oospheres and oospores does 
not vary in the smallest detail. 
The ripe oospores remain dormant dur- 
ing a time which varies from some days 
to some months according to the species, 
and germinate in the same forms as in 
the Peronosporeae (Fig. 69 D, Z). All 
the different forms of germination de- 
scribed in the Peronosporeae have also 
been observed in most of the species of 
Saprolegnieae which have been examined, 
the form varying according to the ex- 
ternal conditions, especially those of nutrition; but in some species certainly only 
one or the other form of germination has been observed. In a new species, Aplanes 
Braunii, the whole course of the development, as far as my observations go, is usually 
