202 
J. Ramsbottom, 
Some recent work on the cytology of fungus 
reproduction. I. 
By J„ Ramsbottom, 
Assistant, Department of Botany, British Museum *). 
Since the introduction of the compound microscope the reproduction 
of fungi has always interested, and at the same time puzzled, investi¬ 
gators. One of the most interesting points is the great variation in the 
reproductive structures — structures which are more or less constant 
throughout most, if not all, of the other great plant groups. Many contro¬ 
versies have waged regarding the sexual processes in fungi, and when 
there has been agreement as to the phenomena, there have still been 
great differences with regard to the interpretation to be given to them. 
As a group, the Phycomycetes have offered the least difficulty, the sexual 
organs being fairly easy to observe. The majority of the old investigators 
held that in most of the genera, a normal process of fertilisation obtains, 
and during the last twenty years this view has been confirmed by various 
workers using modern cytological methods. 
A section of this group, the Saprolegniineae, however, gave great 
difficulty. Certain members of the family possess both antheridia and 
oogonia; others possess only oogonia; whereas still others, which have 
oogonia, may or may not have antheridia the presence or absence of these 
depending upon external conditions. Pringsheim held that normal fer¬ 
tilisation occurred in certain cases, but de Bary (and after him Humphrey, 
Ward, Hartog, and others) considered that the family as a whole was 
apogamous, i. e. that the antheridium, even where present was never 
functional. Trow opposed this view and held that in certain species of 
Achlya he had proved normal fertilisation, but his work was not quite free 
from doubt until 1904, when he clearly showed that a male nucleus fused 
with a female nucleus in the oosphere of Achlya de Baryanum and A. poly- 
andra. Normal fertilisation has since been shown to take place in Sapro- 
legnia monoica (Claussen 1908). Mücke (1908) saw the male and 
female nuclei close together in the oosphere of Achlya polyandra , but he 
did not see actual fusion. 
Kasanowsky (1911) has published an account of his researches on 
Aphanomyces laevis. In this monoecions species both oogonium and 
antheridium are multinucleate. In the oogonium a large central vacuole 
develops which, as it enlarges, forces the protoplasm to the periphery, 
and many of the nuclei degenerate. Those that remain undergo a mitosis 
as also do the nuclei in the antheridium. In each organ all the nuclei 
degenerate except one. The oophere is formed in the middle of the 
oogonium by the gathering of the protoplasm towards the centre round 
a coenocentrum which acts as a centre of nutrition. The female nucleus 
1) A paper similiar in part to the above was published in the Trans. Brit. 
Mycol. Soc. 1911. 
