220 Barker . — The Morphology and Development of 
organs, in the Oomycetes and their presence in Monascus . The 
cells of the latter are, however, multinucleate ; consequently 
the mycelium cannot be looked upon as very highly different- 
iated. Other Ascomycetes, e. g. Erysiphe , moreover, possess 
mycelia consisting chiefly of uninucleate cells. Others, e. g. 
Exoascus ) have very much reduced mycelia. There is thus 
shown in the group of Ascomycetes itself a difference in the 
character of the mycelium at least as great as that between 
the two cases that are being considered. 
The apparent similarity of the zoosporangia of the sporo- 
phyte and gametophyte of Phytophthora omnivor a seems to 
make the ascus, which belongs clearly to the sporophyte, 
equivalent to a typically gametophytic structure. If, however, 
in this species the promycelium is regarded as an elementary 
form of sporophyte — and it has been viewed thus in the present 
discussion — there is a theoretical difference between the zoo- 
sporangia produced by it and those produced by the gameto- 
phyte. The delegation of the special functions of the ascus 
to the former would cause also a morphological distinction, so 
that the ascus is strictly comparable only to them. The others 
have their analogues in the conidia of the Ascomycetes, for 
both are products of the gametophyte, and among the 
Oomycetes conidia and zoosporangia are homologous. Harper 
(11) has pointed out the difference in the methods of spore- 
formation by cell-division in sporangia and asci. In the former 
the protoplasm divides directly by simple fission ; in the latter 
a gradual aggregation of the protoplasm around each nucleus 
occurs. In the sporangium there is thus no epiplasm, while 
in the ascus it is always produced. He regards these facts as 
showing that there is no genetic relationship between sporangia 
and asci. Since the zoospores of a zoosporangium are formed 
by the fission method, the same objection may be raised against 
the homology of this type of sporangium also with the ascus. 
Juel (15), however, believes that the gap between the Phy- 
comycetes and the Ascomycetes is not so wide as indicated by 
Harper’s results, owing to the presence of periplasm in the 
oogonia of the Peronosporaceae, the process of the formation 
