Frey—Physiology of Venturia Inequalis. 
335 
into cells, but his description leads one to believe that he observed 
pores in the cell walls through which the nuclei from the tri- 
chogyne passed, indicating that the archicarp is septate at the time 
of fusion. 
The study of this organism gives further evidence of the correct¬ 
ness of de Bary’s views in regard to the sexuality of the fungi. It 
is impossible to agree with Blackman and Welsford’s idea that 
the sexual organs of the fungi do not function. The appearance 
of the trichogyne in connection with the perithecium and its con¬ 
jugation with the antheridium cannot possibly be considered as 
non-functional. The trichogyne passes from a non-nucleate stage 
to one containing many nuclei at the time of fusion with the an¬ 
theridium, and the cells of the ascogonium become binucleate, 
processes which must be shown to have no relation to the develop¬ 
ment of the asci if we are to accept the theories of Brefeld, Dan- 
geard and Blackman and Welsford. 
The figures of Blackman (1913) are similar to the stages ob¬ 
served in Venturia inaequalis. The similarity of the ascogonium 
of Collema to that of some of the Pyrenomycetes suggests that the 
Ascomycetes and Lichens may be rather closely related, more 
nearly, perhaps, than the Oomycetes and Ascomycetes. Further 
observations of the Pyrenomycetes may confirm the theories of 
Harper and Dodge as to the origin of the Ascomycetes from the red 
algae. The trichogyne is a prominent structure which cannot be 
disregarded, especially as it falls in line with the structures found 
in the Plorideae. The multicelled ascogonium, the trichogyne and 
the ascogenous hyphae and asci have no homologue in the lower 
fungi. We do find some ground for comparison when we study the 
structure of the sex organs in the Plorideae. 
It has not been possible to follow the method of nuclear divi¬ 
sion or the development of the asci. Perhaps the interpretation of 
the processes observed can best be made from the assumption that 
the sex organs are functional, and that the nuclei pair in the as¬ 
cogonium and then migrate into the aseus where fusion occurs. In 
some respects part of the sexual process is analogous to certain 
phases occurring in the Basidiomycetes where nuclear fusion is 
delayed. No evidence of a true sporophytic stage could be found 
in Venturia. Harper (1905) suggests that we consider the tetra- 
sporange of the red algae as a progenitor of the ascus, the car- 
pospores not being comparable to any stage in the Ascomycetes. 
In case the so-called nuclear fusion, which, according to some 
