230 
J. Ramsbottom, 
though at first sight Physoderma seems distant from the other two 
genera because of the total absence of connection between the schizonts. 
It would seem from these several accounts that the longstanding 
problems of cytology and reproduction which the Archimycetes present 
will be cleared up in the immediate future. At any rate it is clear that 
in some cases there is a copulation of zoospores, a phenomenon, the 
presence or absence of which has long been debated. , 
In the Mucorineae , Gruber has taken up the study of Zygo- 
vhynchus Moelleri, but his results do not agree with those of Moreau 1 ). 
Zygospore formation usually begins, as Blakeslee and others have 
pointed out, by the union’of the end portion of an upright aerial hypha 
with a side branch of the same hypha. The end portion, which becomes 
cut off by means of a transverse septum, has usually been interpreted 
as the male branch. Gruber, however regards it as the female, and the 
larger side branch which curves and swells up into a club-shaped struc¬ 
ture in applying itself to this as the male branch. At the place of con¬ 
tact a pear-shaped elevation (the progamete) arises perpendicular to the 
long axis of the female hypha, while the club-shaped end of the male 
branch builds the other progamete. Contrary to Blakeslee’s account, 
a septum was not formed in the male progamete but only in the female. 
A cross septum is now partially laid down about the middle of the 
female gametangium: it arises from the periphery and is rarely completely 
formed usually being soon dissolved. Each gametangium contains numerous 
very small nuclei regularly distributed in a dense cytoplasm. The author 
thinks that in the gametangia nuclear divisions take place during which 
reduction is brought about but this he was unable to demonstrate. In 
the male progamete a portion of the protoplasmic contents containing from 
twenty to thirty nuclei separates off from the remainder. It differentiates 
clearly in staining and is regarded as being the male gamete. It applies 
itself to the membrane separating it from the female gametangium. This 
it dissolves in one place and passes over, amoeba-like, through the small 
opening into the female gametangium, whereupon the opening in the 
membrane soon closes up again. The further behaviour of the nuclei 
could not be followed because of their small size but the author holds it 
probable that the male nuclei fuse with a corresponding number of 
female nuclei. He also suggests that the nuclei in the female game¬ 
tangium might undergo some differentiation into vegetative and generative 
nuclei when that structure becomes partially segmented. Since the 
zygospore (or oospore) contains a very large number of nuclei it appears 
that the fusion nuclei must divide repeatedly. Gruber considers that 
the processes recall what occurs in the Peronosporiineae and the Sapro- 
legniineae , especially Achlya racemosa where Pringsheim saw amoeba- 
like bodies wander over from the antheridium to the oosphères and 
bring about fertilization. He considers that Zygorhynchus can be 
regarded as occupying a position between the Zygomycetes and the 
Oomycetes, the general habit and method of sporangium formation 
showing characters of the Mucorineae. The many small variations 
observed during the study, the vanishing cross wall in the female game¬ 
tangium and the lack of a cross wall at the base of the male gamete 
leave the suspicion that the form dealt with is in a state of variation. 
1) See Mycol. Centralbl. 1912, 1, 204—205. 
