150 
E. A. Bessey, 
Floridean origin of the Ascomycetes so that now the number of botanists 
of this faith is fairly large. 
I will attempt to give a very brief résumé of the chief points that 
would support this hypothesis. First and foremost, as Sachs pointed 
out, the two groups possess in common that type of reproductive structure 
that may be called a “spore fruit“. Whereas in the Phycomycetes the 
result of sexual fusion is the production of a thick walled oospore or 
zygospore, in the Florideae and Ascomycetes, the fertilized oogone (or 
carpogone) grows out into series of cells, few or many in number, often 
associated with sterile cells from other sources and leading to the pro¬ 
duction of the final reproductive structures, carpospores in the one group, 
asci containing ascospores in the other. I will revert later to the details 
of this process in the two groups. In the second place, these two groups 
show many points of similarity, vegetatively. Thus in the Laboulbeniales 
as pointed out by Thaxter and by Faull *), Pyronema according to 
Claussen 1 2 ) and many higher fungi and lichens according to Meyer 3 ) 
and others, the septa of the hyphae are perforated by a single fairly large 
pit which permits of protoplasmic connection between adjoining cells. In 
the Ascomycetes and in the lower Florideae, the structure is prevailingly 
filamentous and, for a large part, the growth of these filaments is ter¬ 
minal. There is also a strong tendency for the cells of the filaments to 
become plurinucleate with age altho they often remain uninucleate. The 
gelatinization of the walls so prevalent in the Florideae is frequent in 
the higher fungi but not by any means widespread. 
In two great particulars however, the groups under consideration 
are very different, namely, their mode of nourishment and the structure 
of their ultimate reproductive cells. The Ascomycetes are without ex¬ 
ception, hysterophytes (i. e. dependent upon external sources for their 
organic food) while the Florideae are typically holophytes. No traces of 
chloroplasts are to be found in the Ascomycetes while they are regularly 
present in the Red seaweeds. However, there are a number of Florideae 
which show transitions from the holophytic to the hysterophytic condition. 
Thus, many are simply epiphytes, apparently using other seaweeds only 
for a place of attachment. Many of these indeed show a tendency on 
the part of the holdfast cells to penetrate rather deeply into the tissues 
of the supporting plant. This becomes very marked in the endophytic 
species, some of which apparently are merely room - parasites, apparently 
obtaining none of their organic food from the plants they inhabit: while 
others, though still retaining apparently functional chloroplasts, are cer¬ 
tainly somewhat parasitic in that the cells of the host plant bordering 
upon the filaments of the parasite are killed or at least emptied of their 
reserve food materials. These examples lead to the case of Harveyella 
mirabilis, which is like the last mentioned except that it contains no 
chloroplasts. It is in fact a fungus, physiologically. Its hyphae branch 
through the host like those of a fungus and indeed the external cushion 
1) FaüLL, J. H., The Cytology of Laboulbenia chaetophora and Z. 
gyrinidcirum (Annals of Botany, April 1912, 26, 325—355; pi. 37—40). 
2) CLAUSSEN, P., Zur Entwicklungsgeschichte der Ascomy ceten , Pyro¬ 
nema confluens (Zeitschr. f. Bot. 1912, 4, 1—64; figs. 1—13, pi. 1—6). 
3) Meyer, Arthur, Die Plasmaverbindungen und die Fusionen der 
Pilze der Florideenreihe (Bot. Ztg. 1902, 60, 139—176; pl. 6). 
