152 
E. A. Bessey, 
and Faull 1 ) deny this fusion for the carpogone and appear to show, for 
the forms with which they worked, that paired but not united nuclei pass 
out into the ascogenous threads, dividing by conjugate division but not 
uniting until the ascus is formed. Yet in this case each pair of nuclei 
has, between them, the diploid number of chromosomes, the union of 
chromatic matter taking place in the Ascomycetes as in the Florideae in 
the synapsis connected with the reduction division. The fundamental 
difference is that in the one case the chromatin masses destined for union 
at synapsis are in separate but closely associated nuclei, while in the 
other case they lie within the same nuclear membrane. Where this change 
occurred, whether as the hysterophytic habit was being assumed or earlier 
or later one can scarcely venture to guess in a matter the whole of 
which is to so large an extent pure speculation. 
Assuming now that it may be likely that the primitive Ascomycetes 
had a Floridean ancestry we must naturally seek for the most primitive 
Ascomycetes among those forms with structures most nearly like those 
of the Algae in question. These we find in the Lichens related to Col- 
lema, as well as in the Laboulbeniales. In both of these groups the 
occurrence of non-motile sperm cells and trichogynes has often led to 
the belief in the relationship of these fungi to the Red seaweeds. Collema 
is of especial interest in view of the discovery by Miss Bachmann 2 ) that 
in one species the sperms are not set free from the antherid but are 
sought out by the trichogynes which partially wind around them and then 
fuse with them. This forms an easy transition to the types like Pyro- 
nema where the antherid forms no sperm cell at all but fuses directly 
with the trichogyne. By a gradual reduction of the latter we approach 
types like the Erysiphaceae in which a trichogyne is lacking. 
Even in the Florideae the trichogyne is sometimes a separate cell 
from the carpogone. This is strongly marked in the case of those Asco¬ 
mycetes in which this organ occurs, it often containing four to six or 
mere cells. The formation of a several celled ascogonium, the cells of 
which may fuse more or less is perhaps an indication that the ancestral 
Florideae were of the type in which auxiliary cells were present. This 
is of course mere surmise until the nuclear phenomena in forms with a 
true ascogone have been worked out fully. 
Based on the foregoing I would suggest that the algal ancestors of 
the Ascomycetes were Floridean in nature, probably inhabitants of fresh 
water, that were first epiphytic, then endophytic and finally parasitic 
within colonies of Nostoc. They gradually emerged and acquired the 
power of land life in connection with this or similar hosts. The most 
primitive spore fruit, then, of the Ascomycetes would be the apothecium 
such as found in Collema or similar Lichens , a structure resembling the 
cystocarp of many red seaweeds. In the one direction this type of 
structure became more and more perithecioid, until we have a true peri- 
thecium. This progressed further to the closed structure of the Erysi¬ 
phaceae and the spore fruits such as occur in Aspergillus , the Tuberaceae 
1) Claussen, 1. c. — Faull, 1. c. — Schikorra. W., Über die Entwick¬ 
lungsgeschichte von Monas eus (Zeitschr. f. Bot. 1909, 1, 379—410; 3 Textfig., 
2 Taf.). 
2) Bachmann, Freda M., A New Type of Spermagonium and Ferti¬ 
lization in Collema (Ann. of Bot. 1912, 26 [Jy.], 747—760; pi. 69). 
