FAULL: DEVELOPMENT OF ASCUS. 
109 
Saprolegniineous zoosporangium, then it seems unnecessary to 
regard it as a new feature. As to its origin from a carpospore 
there are few known facts on which to base a conclusion, and such 
as are known are to the effect that the carpospores are uninucleate 
from the first, and continue to be so to the end. 
Of the four suggestions offered, the facts of spore formation that 
have been adduced up to the present, seem, in the opinion of the 
writer, to favor the one that homologizes the ascus with the Oomy- 
cetous zoosporangium. If established, it is a strong argument in 
support of the theory that the Ascomycetes have been derived 
from the Oomycetes. Such a conclusion, however, can scarcely be 
considered as final, for as was indicated in the opening jjaragraph 
of this section, the phenomena of sexuality are equally important in 
determining the origin of the group, and deserve equal consider¬ 
ation. It is outside the purpose of the present paper to discuss that 
side of the subject, though it may be added that De Bary on the 
basis of sexuality arrived at the conclusion that there is a probability 
of the phylogenetic relationship of the Ascomycetes with some such 
Phycomycetous group as the Peronosporineae or Saprolegniineae. 
Summary. 
1. The asci bud out from the penultimate cells of the ascogenous 
hyphae in some forms, in others from the terminal cells, and in a few 
species apparently from any cell. 
2. In every case that was definitely determined, the uninucleated 
stage is preceded by a fusion of two nuclei within the ascus. The 
conjugating elements, though not sisters, may sometimes be the 
daughters of sister nuclei. 
3. The age and development of the asci at the time of fusion vary 
considerably in different species, and to some extent, though within 
narrower limits, in the same plant. 
4. Extranuclear bodies or granules, evidently of nutritive matter, 
the staining reactions of which are very similar to those of the 
nucleolus, are formed in the young asci in the neighborhood of the 
nuclei, and probably through their activity. They disappear before 
the spores are matured and in many forms during the first spindle 
stage. Similar bodies frequently occur in the ripe spores. 
