FAULL: DEVELOPMENT OF ASCUS. 
Ill 
9. After a period of growth and storage of reserve matter, an 
exospore is formed between the two opposed plasma membranes. 
10. In the meantime the following changes may take place in 
the spores, according to the species to which they belong: (1) 
karyokinetic division of their nuclei without the formation of septa; 
(2) nuclear division followed by a corresponding septation ; (3) the 
cutting off of an enucleated part of each spore, as in Podospora, by 
a septum, the organization of which is due to the direct action of 
the nucleus on the cytoplasm in its neighborhood. 
11. The evidence points to the conclusion that while the ascus 
has probably not been derived from the sporangium of the Mucor- 
ineae, the phenomena of spore formation are not incompatible with 
the view that homologizes the ascus with the zoosporangium, nor 
with the view that the Ascomycetes have originated from some such 
Phycomycetous group as the Peronosporineae or Saprolegniineae, 
an affinity first suggested by De Bary on the basis of sexuality. 
The investigations recorded in this paper were begun in the Lab¬ 
oratories of cryptogamic botany at Harvard university under the 
direction of Prof. Roland Thaxter, to whom I am under deep obli¬ 
gations for material and advice. My best thanks are also due Prof. 
W. G. Farlow and Dr. E. J. Durand for assistance in determination 
of species, Prof. E. C. Jeffrey for specimens of Tuber and Balsamia, 
and Professors C. B. Davenport and D. S. Johnson for facilities 
afforded in collecting material at the Biological station of the Brook¬ 
lyn institute of arts and sciences at Cold Spring Harbor, L. I. 
