310 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 
In Phycomyces, after the partitioning of the cells to form 
the zygospore, a number of dichotomously branched processes 
are developed from the conjugating filaments.’ Van 
Tieghem and Le Monnier point out that these processes are 
not developed simultaneously on both conjugating filaments 
and they trace in this a first step in sexual differentiation. It 
may be suggested also that the formation of the branched 
processes which form a kind of investment of the zygospore 
is a kind of anticipation of the more elaborate developments 
of the same kind met with amongst the Carposporee. 
Sorokin has also discovered a Chytridineous plant Zygo- 
chytrium which produces zygospores by the union of fila- 
ments instead of zoospores.? This proves that there is no 
absolute distinction between the two processes. 
Class I11.—OospPorE®. 
Ir, as already pointed out, the two similar elements which 
take part in a conjugation become differentiated, we pass 
without difficulty from the formation of a zygospore to that 
of an oospore. For aught we can see to the contrary, the 
quantitative and qualitative factors are equally balanced in 
the one case, but it is evident that they are unequally so in 
the other. The oosphere is generally enormously larger 
than the antherozoid, which consequently can do little more 
than give the oosphere some kind of impulse. Amongst the 
Zygosporee either the entire protoplasmic contents of two 
cells of equal size take part in the conjugation, or at any rate 
fractions of their contents of equal value do so. It is part 
of the essential difference of the Oosporee that while the 
oosphere represents the entire contents (or in Fucacee a very 
large fragment) of a single cell—the oogonium, the anthe- 
rozoid is only a very minute fragment of the contents of the 
unicellular antheridium. 
VotvocinEm.—If we compare the whole series of forms 
usually included in this group (but which is here restricted 
to Eudorina and Volvoz) it appears to offer a complete 
transition from the zygospore to the oospore. Sachs preserves 
a complete silence with regard to these genera, yet both are 
furnished with distinct antherozoids discharged from an 
antheridial cell. 
According to Carter in Eudorina, the contents of the four 
cells adjacent to one pole of the colony undergo conversion 
into antherozoids, make their escape from the parent cell, and 
“freely come into contact with the capsules of the twenty- 
1 See ‘ Quart. Journ. Mic. Sci.,’ 1874, pp. 63, 65. 
2 «Quart. Journ. Mic. Sci.,’ 1874, p. 298. 
