1906] OVERTON—THECOTHEUS PELLETIERI 479 
for certain Peronosporaceae. It seems apparent that, even if we 
accept FAuLt’s description of spore formation in the ascus, the data 
are quite insufficient to support any view which homologizes the ascus 
with the zoosporangium or oosporangium of the Oomycetes. 
BARKER (:04) announces that the protoplasm in the developing 
ascus of Ryparobius shows a series of changes in spore formation, 
which appear to be intermediate between typical methods in spor- 
angia and asci. The account is only preliminary and has been referred 
to above. My own studies on the asci of Thecotheus however, have 
shown the process of spore formation to be as in other typical asci, 
namely, by means of the kinoplasmic radiations of the nucleus. 
Although more than eight spores are formed in the ascus, the process of 
spore delimitation is that found in a typical ascus. There is abso- 
- lutely no evidence that the process is in the least similar to spore 
formation as found in the sporangia of the Oomycetes or in those of 
the Phycomycetes. The results obtained do not seem to throw the 
least light on the homology or origin of this peculiar organ. It 
apparently makes no difference whether less than eight spores are 
formed or more than eight, the phenomena of spore delimitation are 
exactly the same as found in typical eight-spored asci. 
That a true alternation of generations, comparable to that found 
in the higher plants, exists among the Ascomycetes, is certainly obvious 
from the fact that the asci eventually arise as the result of fertilization. 
DEBary (70) advanced the opinion that the ascus fruit represents 
an asexual generation, and WoRoNIN (’70) compared it to the spor- 
ogonium of the moss, which idea was farther emphasized by HARPER 
('96) for Erysiphe. The only essential difference is that the egg is 
never separated from the parental tissue system, agreeing in this 
Tespect with that of the red algae. HARPER also pointed out that 
the ascus is an analogue of the spore mother cell of the higher plants, 
and that the triple division corresponds to the double division in the 
Spore mother cells of the higher plants, with a probable consequent 
chromosome reduction in the ascus. This view is further supported 
by the recent discoveries of MAIRE (:05), Harper (:05), and GuiL- 
LIERMOND (:05) on the nuclear phenomena in the ascus, by which 
Teduction of the number of chromosomes and a consequent return 
to the gametophyte generally occur. These authors have found 
