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Some recent work on the cytology of fungus reproduction, II 
225 
be the stage just before zoospore formation but Kusano records here as 
in Synchytrium Puevariae (1909) that further growth takes place increasing 
the amount of cytoplasm and the number and size of the nuclei, the 
mature condition being representend by a dense consistency of the cyto¬ 
plasm. In no case was a typical mitotic division observed during the 
growth stage; the divisions resemble amitosis but there is a disappearance 
of the nuclear membrane and the chromatin as well as linin. “It is 
very likely the “Promitose” proposed by Naegler in the nuclear division 
of Amoeba .” During the reproductive stage mitotic division takes place. 
The nucleolus disappears but the exact processes were not made out. 
This difference in the two divisions is already known in other Chytridiales 
and in the Plasmodiophoraceae. Zoospore formation was not fully 
investigated “as the minuteness precludes an exact observation”. 
Among the spherical naked bodies in the host cells are found 
certain larger ones which are binucleate and have arisen from the encysted 
zygote. In the earlier stages only a small nucleolus is prominent in the 
nucleus. Later the nuclear membrane becomes clearer, the enlarging nucleolus 
becomes vaculate and disc-shaped, and on maximum size being attained, the 
linin threads and chromatin granules become conspicous, assuming a reticu¬ 
lated structure. When fully grown, a membrane appears on the surface of the 
resting sporangium, its centre is occupied by a large vacuole and the two 
nuclei occupy peripheral positions usually opposite to oneanother (ef. zygote of 
Polyphagus). The nucleoli now appear as if displaced outside the nuclear 
membranes, and a nuclear budding takes place at the tip of the nucleolus. 
“This bud gradually increases in size and can attain nearly the form and 
size of the mother-body, resulting in the formation of a dumb-bell-shaped 
nucleus with the nucleolus in the median position. Later the budded 
portion disintegrates, its wall is broken and the contents are thrown into 
a central vacuole.” Afterwards these dissolution products begin to be 
distributed from the vacuole into the surrounding cytoplasm. The vacuole 
becomes replaced by highly stainable cytoplasm, and the resting period is 
entered upon. Just before germination the cytoplasm appears homogene¬ 
ously granular and hardly stainable. “Among such sporangia we find 
several stages of the nuclear feature indicative of karyogamy.” A few 
sporangia were found in which only a single larger nucleus occurred centrally 
situated. Stages of fusion were difficult to observe. The author thinks 
that the first divisions of the fusion nucleus are karyokinetic and represent 
reduction divisions. The stages are difficult to make out as the nuclei 
exhibit only an obscure outline and give no definite figure. 
Nèmec (1911) working with Olpidium Salicorniae has obtained 
results which are very interesting in the light of the researches of Griggs 
and Kusano. The first stages observed were naked uninucleate cells 
with at first dense, granular cytoplasm which later becomes vacuolate. 
The nucleus is large and contains an ellipsoidal, strongly staining nucleolus. 
The naked cells become cither zoosporangia or resting sporangia. In the 
first case the nuclei increase in number, the parasite surrounds itself 
with a rather thin membrane and its contents break up into a large 
number of uniciliate swarmspores. These appear to be all of the same 
size and posses a nucleus which frequently sends off a short process to 
the base of the cilium pointing to a connection between the two. In 
other cases resting cysts arise from the naked parasites. They possess 
Mycologisches Centralblatt, Bd. III. 15 
