Frey—-Physiology of Venturia Inequalis, 
323 
that the Ascomycetes must have arisen from the Florideae. He 
bases his conception on the similarity of the archicarp, especially 
the trichogyncj to the corresponding organs in the Florideae. The 
difficulty in accepting this view arises from the lack of evidence 
as to the origin of the ascus, no equivalent organ having been found 
in the Florideae^ unless we consider ooblastema filaments as homol¬ 
ogous to ascogenous hyphae. Speculations^ at present, are only 
worth while in so far as they stimulate further research. It is 
entirely possible that a large number of forms are present in na¬ 
ture, still undiscovered, which will supply the missing links. If 
such forms cannot be found our theories, like those on the origin 
of man, will ever remain the subject of dispute. The search for 
homologies in the evolution of the sex organs offers the most plaus¬ 
ible method of attack. One would expect the vegetative organs to 
respond to immediate environmental changes whereas the genera¬ 
tive organs or cells may not fundamentally alter. 
Atkinson (1916) in a very detailed discussion attacks the views 
of Sachs on the origin of the Ascomycetes. He finds it impossible 
to accept the view of the origin of the Ascomycetes as being de¬ 
rived from the red algae. There is, according to him, no homology 
existing between the archicarp and the procarp. The ascus might 
develop from forms similar to Dipodascus by branching of the 
zygogametangium. By reducing the number of spores in the ascus 
of an organism of this type forms like Eremascus and Endomyces 
are produced. The trichogyne, Atkinson contends, is not a func¬ 
tional organ in most of the Ascomycetes studied, and may have de¬ 
veloped rather as an outgrowth, or beak of the oogonium, a condi¬ 
tion often found in certain oomycetes when the female organ is 
stimulated. In the Laboulbeniales the trichogyne is highly devel¬ 
oped but does not always function. The septa prevent nuclear 
migration and thus it occurs that many Ascomycetes' that retain 
the sexual organs may not have nuclear fusion. Many Ascomy¬ 
cetes that retain functioned gametangia do not possess a trichogyne. 
In cases in which the sperm enters the trichogyne there is no evi¬ 
dence that this process is necessary to initiate disintegration, as it 
may proceed without it and cannot be cited as proof of fertilization. 
In such forms as Monascus he regards the antheridium as an 
elongated terminal cell of a hyphae and homologous with a chain 
of conidia. This conception harmonizes such anomalous forms as 
Collema in which the trichogyne fuses with a spermatium or 
conidium. 
