16 
Ohio Biological Survey 
above the non-algicolous forms because of their higher somatic develop¬ 
ment and the general resemblance between their sexual reproductive 
tracts and those of the pyrenomycetes above them. In so doing, it is 
plainly seen that any method that could be followed is open to criticism 
and liable to be proved incorrect by further research. 
The resemblances between the sex organs of the Ascomycctae and 
the Rhodophyccac have been a matter of repeated discussion since the 
time of Stahl’s work on the Collemaccae and have been greatly empha¬ 
sized since by the researches of Thaxter (61), Bachman (1 and 2), 
Dodge(24), and others. The ascogenous hyphae of the Ascomycctae like¬ 
wise have been homologized with the ooblastema filaments of the 
Rhodophyccac, while a relationship has been suggested between asci and 
the gonidioblasts which arise as the result of secondary fusions among 
the red algie. If the evident parallelism in development among the 
Ascomycctae and the Rhodophyccac rests on supposed homologies, we 
may also conclude that ascocarps and cystocarps are homologous struc¬ 
tures, and that the former group arose from the latter, or that the two 
groups had at least a common origin. One of the two suppositions just 
stated must be adopted, or we must follow those who think that these par¬ 
allelisms do not rest upon homology. This matter is fully treated by 
Dodge (24). 
In this connection, it might prove worth while to reexamine the 
forms of parasitism found among the Rhodophyccac, and reproductive 
and somatic tracts in these parasitic algae, with a special view of attempt¬ 
ing to shed some light on the problem of possible affinities between the 
Rhodophyccac and the Ascomycctae. It is even possible that, if asco¬ 
carps are to be homologized with glomerules and cystocarps, and much 
more fundamental and significant homologies exist between structures 
which lead up to these mature fruits, such studies would indicate a 
multiple origin of the Ascomycctae from the Rhodophyccac and suggest 
that more than one type of ascocarp may be primitive. Such studies 
might also help to decide whether forms of ascomycetes which have simi¬ 
lar ascocarps are all closely related, or whether certain groups which have 
very different ascocarps are not sometimes nearly related. 
^^4latever the future may prove regarding the various possible or 
jirobable homologies between the Ascomycctae and the Rhodophyccac, it 
is certain that the theory of the origin of the former from the latter is the 
most plausible one that has been offered regarding the phylogeny of all 
undoubted ascomycetes, algicolous and non-algicolous. 
Cytological studies must prove increasingly valuable in our studies 
