FAULL: DEVELOPMENT OF ASCUS. 
107 
ated concurrently with the growth of the nuclei, and frequently with 
their reconstruction, and that these changes are taking place in the 
same direction as that in which the nuclei are elongated. The 
question of the part played by the astral rays, however, is a more 
serious one. That they certainly do not form the limiting mem¬ 
brane but are enclosed within the spore is maintained by the obser¬ 
vations recorded in this paper. But this does not entirely dispose 
of them, for it may be suggested that they serve to direct the delim¬ 
itation of the spore, especially the laying down of the limiting layer 
of protoplasm (though not forming a part of it) which marks out 
the cleavages to follow or as Berlese (’99) thought, of the plasma 
membrane itself. If they are visible expressions of nuclear forces, 
that is possible, though rather indicative of cytoplasmic activity under 
nuclear control in the region in which they lie than of an activity 
or force within themselves. The variability of their appearance 
leaves it open to question that they are at all essential to the proc¬ 
ess or take any share in it. In Ilydnobolites they are pronounced; 
in PTeotiella albocincta they are not abundant, and are very tenuous 
and difficult of demonstration, and Guilliermond (:03a) claims that 
in Peziza rutilans they are entirely absent. Indeed, the function 
of astral rays in the ascus remains the same debated question as in 
other places in which they occur. 
As to the second and third objections, namely, in regard to the 
nature of the delimitation of the spores, and of their plasma mem¬ 
branes, my observations indicate that in both zoosporangium and 
ascus the process of delimitation is practically the same, — a cleav¬ 
age, — and that the plasma membranes are the same, and not in the 
one a fusion of astral rays. The point from which cleavage starts 
is a secondary matter. Within the Phycomycetes themselves there 
is great variability, the cleavages beginning from inner or outer 
plasma membranes or even from vacuoles. Whether or not the 
plasma membranes about the spores are entirely formed de novo in 
one case and not in the other, seems of little account, granted that 
they are the same and formed in essentially the same way. 
The last objection has to do with epiplasm, its absence in the 
sporangium and its presence in the ascus. In the former the plasma 
membranes on either side of a cleft enclose a young spore, while in 
the latter but one of them performs that function, the other lining 
a cavity in the non-nucleated epiplasm. This epiplasm has been 
