456 BOTANICAL GAZETTE [DECEMBER 
chia, Endocarpon, Gyrophora, Lecanora, and Cladonia arising from 
carpogonia similar to those of Collema, so that these forms also 
probably possess sexual organs. Solorina is probably apogamous, 
behaving in this respect like Peltigera peltidea and Nephromium as 
described by FUn¢sttck (:02), in which trichogynes have disappeared. 
SCHULTE (:04) has studied the structure of several species of Usnea. 
In U. longissima he claims that the asci do not arise from the asco- 
gonia, although several are present. Trichogynes and spermatia 
could not be found in U. microcarpa. 
The presence of trichogynes, spermatia, and carpogonia similar 
to those of the red algae, and also ascogenous hyphae which arise from 
carpogonia, all indicate the presence of an undoubted functional 
sexual apparatus in the lichens, although the important phenomena 
relating to nuclear behavior still remain unsolved. 
GUILLIERMOND (:05) has discovered a nuclear fusion accompany- 
ing cell fusion in certain yeasts which he holds to be sexual. Conju- 
gation of conidia and nuclear fusion take place in the Schizosac- 
charomycetes and Zygosaccharomyces just before spore formation, 
while in certain other forms (S. Ludwigii, etc.) the same phenomena 
occur at the time of spore germination. In the Schizosaccharomy- 
cetes and Zygosaccharomyces two cells become connected by a con- 
jugation tube in which nuclear fusion occurs. The fusion nucleus 
divides immediately and the two daughter nuclei separate, one enter- 
ing each original cell, in which a double division occurs to form the 
four nuclei of the four so-called ascospores. In certain other yeasts, 
such as S. Ludwigii, projections are put out from contiguous spores 
in the ascus, fusing to form a canal in which nuclear fusion occurs. A 
promycelium is developed from this conjugation tube, which buds 
off conidia. GUILLIERMOND considers the phenomena here presented 
as the conjugation of isogamous gametes, in the one case before and 
in the other case after the formation of the asci. In the one case, 
S. Ludwigit, yeast of Johannisberg, and S. saturnus, the sporophyte 
with the double nuclear characters is the ordinary vegetative budding 
stage of the yeast, while in the other case (Schizosaccharomycetes 
and Zygosaccharomyces) this vegetative stage is the gametophyte. 
The most recent investigations on the Ascomycetes and rusts indi- 
cate an undoubted alternation of generations in these groups. It 
