Some recent work on the cytology of fungus reproduction, II 
231 
Moreau (1912) immediately criticised Gruber’s results. “Nous 
n’hésitons pas à dire que Grüber a été la victime d’une erreur.” He 
considers that the large suspensor of Z. Moelleri has been mistaken for 
a reproductive structure: that the general method of zygospore formation 
in the Mucorineae has been disregarded: that it has been forgotten that 
the fusion in all cases studied (in particular three species of Zygorhynchus 
near Z. Moelleri) presents all the characters of a gametangium, and that, 
lastly, all the homogeneity which the Mucorineae owe to the characters 
of their reproductive structure is taken away. Moreau’s work was 
known to Gruber when he published his results and must have been 
considered as it is mentioned by him 1 ). 
Me Cormick (1912) has published a preliminary account of her 
work on Rhizopus nigricans (isogamous and heterothallic). Namylowski 
(1906) worked at a species which he considered the true R. nigricans 
but found it indifferently isogamous or heterogamous, and homothallic. 
Each gametangium contained large numbers of nuclei but neither division, 
copulation, nor disintegration of nuclei were seen. Me Cormick found 
that the young gametangia each contained numerous nuclei. The walls 
cutting of the gametangia from the suspensors may not be formed 
simultaneouly and in each wall there is left a central pore. The wall 
which separates the gametangia from each other often thickens considerably 
before disintegration, and fragments of the thickened wall may be found 
in quite old zygospores. The many nuclei from each gametangium 
increase in size after the disintegration of the wall. All the nuclei except 
two disintegrate and these two nuclei are embedded in a coenocentrum. 
There are indications that the coenocentrum has its origin at the point 
of contact of the two suspensors before the gametangia are cut off. 
Neither fusion nor division of nuclei have yet been observed. Me Cormick 
believes that the two nuclei left in the coenocentrum fuse. “From this 
stage to maturity many changes appear in the appearance of the zygo¬ 
spore, but their interpretation is not yet quite clear. The coenocentrum 
persists until quite late, and in the mature zygospore there are many 
nuclei of the same size as those in the mycelium.” This account of the 
fusion of two nuclei seems to agree with that of Lendner (1908) for 
Sporodinia grandis. Here, however, is the first record of a coenocentrum 
occurring in the Mucorineae though its presence is so very common in 
the Oomycetes. 
Moreau (1913) has published a full account of his studies on the 
Mucorineae. First considering the case of asexual reproduction, he 
divides the group into a) those with sporangia, b) those with conidio- 
phores and c) those in which the endogenous or exogenous origin of the 
spores is disputed. Many observers have studied the cytology of the 
sporangia. Harper (1899) laid the foundations of our present knowledge 
when he showed that although the ripe spores of both Pilobolus and 
Sporodinia were plurinucleate, in the former case the protoplasm frag¬ 
mented into uninucleate segments (protospores) which later became pluri¬ 
nucleate, in the latter the segments were plurinucleate from the beginning 
Moreau finds that the spores in Circinella conica, Mucor spinescens, 
Absidia glauca , A. septata and Zygorhynchus Moelleri , are at first 
1) For a critism of Gruber’s work from a morphological standpoint see 
Blakeslee, Mycol. Centralbl. 1913, 2, 241—244. 
