166 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI. 
A second series of forms are intracellular parasites in the living and otherwise sound 
foliage of some of the marsh plants infested by the first mentioned group. They form 
brown spots or pustules on the leaves, and spread from cell to cell, and often produce a 
large number of sporangia in each cell without coming out to the surface of the plant. 
To this group belongs the form which has been described as Protomyces Menyanthis, 
and another which may be named provisionally Cladochytrium Iridis. All the 
sporangia in these two species are converted, as the mycelium disappears, into thick- 
walled often brown ellipsoid resting-spores (Fig. 77), which, as far as is known, germinate 
only after hybernation and then form swarm-spores. This was observed by Goebel, as he 
informed me by word of mouth, in Cladochytrium Menyanthis, and by myself in C. Iridis. 
The germination of the swarm-spores has not yet been observed. 
The occurrence of members of both these groups in the tissue of the same plant, as 
for example in Iris Pseudacorus, might lead to the supposition that the forms of the first 
group belong to the same species as those of the second which form resting-cells ; but 
there is no fact to show this, and it is opposed to the observation that a large number 
of swarm-spores of Cladochytrium Iridis will not germinate even on dead tissue of Iris 
Pseudacorus. They seem to require living cells for their further development, but 
I could not see that they made their way into them. 
No act of conjugation and no sexual organs 
have been observed in these plants. In the 
formation of intercalary sporangia and resting- 
cells it is often observed, that an intercalary 
swelling of a branch of the mycelium first 
appears and is then divided by a transverse wall 
into two halves; one of these halves swells into 
a sporangium, while the other does not enlarge 
and loses its protoplasm. But it cannot be 
seen that the protoplasm has passed over, as 
might be supposed, into the half which is in- 
creasing in size, it seems on the contrary to 
Fic. 77. Cladochytrium Iridis. a a resting-spore travel into the growing mycelium ; and on the 
with a brown membrane seen from the broadside. dthe other hand the whole of the p art that swells at 
same rotated through 90°; in its centre a large sphere 
of fatty matter. c—es ivestagesof germinationof first often becomes a sporangium or resting-cell 
a resting-spore ; the inner cell developes into a tubular A a oe. 
swarm-spore-receptacle, when the brown outer membrane without previous transverse division. The con- 
has opened by a lid. @ completion of the formation of = ed : : 
the spores. e exit of the spores. /asingle swarm-sporc. Jugation of the Swarm-spores, which might also 
ae magn. 375, 7'500 times, be expected from analogy, has not been ob- 
served. 


The forms of Physoderma, Ph. maculare, Wallr. inhabiting Alisma graminifolium, 
Ph. Heleocharidis, Fuckel, Schröter’s (1882), Ph. Butomi and Ph. vagans, the latter of 
which is found in different Phanerogams (Potentilla anserina, Ranunculus flammula, 
&c.), are very like Cladochytrium Menyanthis and C. Iridis as regards the intracellular 
development and the structure of their resting-spores in the inner layers of the 
parenchyma of the leaves oftheir host. But these species according to Schröter have 
no mycelium; the single resting-spore is formed in the same way as in Synchytrium. 
We are not told how their primordia find their way into the interior of the cells. 
Section XLIX. 3. Olpidieae. We are indebted to A. Fischer for a com- 
plete account of the development of Olpidiopsis Saprolegniae and O. fusiformis, 
Cornu. The former plant causes a pouch-like swelling in the tubes of the 
Saprolegnieae which it inhabits, and in its full-grown state is an ellipsoid or round 
cell which forms neither rhizoids nor mycelium, but ultimately becomes a sporangium 
and discharges its zoospores through one or more cylindrical necks which pierce 
