68 BOTANICAL GAZETTE [JULY 
of sexuality in the Ascomycetes, and that the phycomycetous ancestors have trans- 
mitted to the higher fungi only the asexual stage. Since asexual conidiophores 
are numerous in the Ascomycetes, the primitive aerial sporangium must have 
developed along two different lines, giving rise on the one hand to the ascus and on 
the other to the conidiophore. 
According to the second theory, that of pr Bary, the ascus is either the whole 
or part of a multicellular structure, the sporocarp, which is the product of the 
fertilization of an archicarp. The latter is a cell capable of being fertilized, and 
finds its homologue in the receiving gamete of the alga, bryophyte, or fern. 
sporocarp corresponds, therefore, to the oospore or zygospore of the green alga, 
the sporogonium of the bryophyte, or the leafy plant of the fern. In other 
words, it is the sporophyte. If all the Ascomycetes developed their asci in the 
manner of Dipodascus or Eremascus, this conception of the organ as a sporo- 
gonium or sporophyte would hold true, since in these plants the ascus arises 
directly from the fertilized egg. But Dr Bary believed that in the greater num- 
ber of the Ascomycetes the archicarp gives rise to the whole perithecium, so that 
the ascus in these cases is not an entire sporogonium but only a part of it, and he 
regarded it as the equivalent of the spore mother cells in the bryophyte or fem. 
But it would be remarkable if an organ of such uniform structure should corre- 
spond in some cases to a whole sporogonium, and in others to a mother cell 
only; and pr Bary was in error in thinking that it could be either one or the 
other according to circumstances. ; 
As to the third theory, the author remarks that, however strange it may seem 
to homologize asci with spore mother cells, it must be admitted that a certain 
analogy exists in the limited number of divisions in the ascus to form the spores- 
If the whole perithecium really arose from the fertilization of an egg, no serious 
objection could be urged against this homology. But the fruiting body of the 
Ascomycetes has a mixed origin, since part of the envelope is formed from fila- 
ments of the gametophyte. The following additional facts are regarded as antago 
nistic to this view: (1) In the small number of genera in which the gametangia 
are still functional, the egg gives rise directly to the ascus, as in Dipodascus; (2) 
in the other genera the gametangia are no longer functional, and the perithecium 
does not develop from the egg; (3) the formation of the ascus is always preceded 
by a fusion of nuclei, and no case is known in which the formation of mother cells 
is preceded or accompanied by a phenomenon of this kind; (4) in the lower 
siphonaceous fungi, from which the Ascomycetes have arisen, there is no orga? 
which corresponds to mother cells, but one finds on the contrary the sporogonium 
(oospore, etc.), which is evidently the ancestor of the ascus. ; 
Much discussion is devoted to HARPER’s contention that the fusion of nucle! 
which precedes the formation of the ascus is without sexual significance. Fee 
points are considered in this connection: (1) the binucleate structure of the ascuS; 
(2) the fusion of the two nuclei into one; (3) the reduction in the number of 
chromosomes. Against HaRPER’s contention, that the binucleate condition of 
the ascogenous cells is the result of the stimulus of excessive nutriment, it is urge 
