on species of Tolypothrix. 653 
nous n’avons jamais reussi a voir une cloison quelconque V 
Dangeard’s figures 129 and 30 give no indication of a fusion 
between protoplasmic masses or nuclei in the formation of 
the spores (with the possible exception of Fig. 30), nor does 
he state that he has seen anything of the kind. His assump- 
tion that they are sexually-formed zygospores is based on 
a comparison with Maxime Cornu’s and with Zopf’s figures 
of Myzocytium and Lagenidium respectively; and he adds 
that ‘ nous devons noter toutefois que la differentiation sexuelle 
est bien faible et que, dans beaucoup de cas, il devient impos- 
sible de la saisir ’ (loc. cit., p. 99). 
Fischer (’ 92 , p. 85) remarks that, according to Dangeard’s 
description, ‘ die Sexualorgane in der Weise entstehen, dass 
in einem aufgeschwollenen Fadenstiick das Protoplasma sich 
in zwei gleiche Theile verdichtet, die mit einander verschmelzen 
und die Dauerspore (Zygospore) erzeugen.’ Dangeard says 
nothing about a fusion, although, by his calling the thick- 
walled cells zygospores, he tacitly assumes its occurrence. 
I can see no reason for regarding these spores as having 
been sexually produced. They are merely formed by an 
increase in size of a part of the ordinary mycelium, and the 
fact of their sometimes being formed in groups of three, four 
or five together alone speaks against their sexual origin ; for 
there are no traces of empty antheridial cells between the 
individual spores in such cases. It is true that the young 
stages often have a sort of pear-shaped form, so that there are 
apparently a large and a small swelling side by side (cp. 
Fig. 18 of R. Boodlei ) ; but in these cases the fully-developed 
spore has the same shape (Figs. 20, 21), and I was unable to 
detect a differentiation into two protoplasmic masses in the 
earlier stages. 
There is one further point, which I think speaks very 
strongly against the sexual origin of these spores. I have 
already mentioned that some branches of the parasitic hyphae 
1 It is not quite plain to me, whether Dangeard is referring to the entire hypha, 
in whose course the spore is formed, or to the non-occurrence of a division-wall 
between the assumed sexual organs ; if the former is the case, this is a point of 
difference between R. nodosa and the form I am describing. 
