224 Barker . — The Morphology and Development of 
‘ sporangium ’ homologous, whereas it has been shown that 
the kind of homology between these structures is one between 
the whole group of asci, regarded as a unit, and the single 
‘ sporangium.’ Ought not, accordingly, the zoosporangia of 
the Oomycetes to be classed in a similar manner into two 
groups, which might be called respectively the mega- and 
the micro-groups ? The mega-zoosporangium would, in this 
way, be looked upon as being formed from the whole or 
a portion of the thallus by the direct conversion of this into 
a sporangium ; while the micro-zoosporangium would be 
formed by a differentiation of the former into sporogenous 
and vegetative parts, the sporogenous portions constituting 
the zoosporangia and being formed as specialized branches 
of the latter. Two kinds of zoosporangia are found among 
the Oomycetes. viz. the large sporangia of the Saprolegniaceae 
and the small conidium-like sporangia of the Pythiaceae and 
the Peronosporaceae. They may be taken as furnishing respec- 
tively examples of mega- and micro-sporangia, and the homo- 
logies as being between the sporangium of the former and the 
combined conidiophore (or sporangiophore) and conidia (or 
sporangia) of the latter ; thus furnishing an example com- 
pletely parallel with that of the ‘ hemi-ascus ’ or e sporangium ’ 
and the ascus. The existence of such a form as Dipodascus 
must hence supply a strong argument in favour of the hypo- 
thesis of a relationship between the Oomycetes and the Asco- 
mycetes. The organism itself can hardly be regarded as an 
intermediate form between Monascus and the nearest Oomy- 
cete, on account of the distinctions drawn above between asci, 
hemi-asci, mega- and micro-sporangia : it is, rather, a parallel 
form, but closer to its Albugo type than Monascus is to 
the Phytophthora type for reasons given above. It is, in 
addition, of importance as forming a link between the other 
Hemiasci, which are all asexual forms, and the sexual Asco- 
mycetes. The relationship of these two groups follows from 
the above. 
The Gymnoascaceae, although simple in structure, do not 
appear to stand in a position intermediate between Monascus 
