306 Wager . — On the Structure and 
that it spreads unequally, then the wall of the oospore 
becomes unequally thickened, and the ridges may become 
so pronounced as to look like warts. The fertilizing tube 
of the antheridium also becomes surrounded by a thick 
exospore. 
The exospore begins to take a brown colouration when the 
projections are yet small ; it is already quite dark brown 
when these are uncoloured, the latter requiring a longer time 
to attain to the brown colouration. 
So far as the author’s observations go it takes probably 
from eight to ten days from fertilization to the ripening 
of the oospore. 
He does not accept Cornu’s observations as to the structure 
of the wall of the oospore. The endospore consists of pure 
cellulose. The exospore is cuticularized. In the majority 
of cases, as in C. candidus , the exospore consists of four 
layers. 
The thickness of the separate layers differs in the different 
species. The inner layer is thin homogeneous and cuticu- 
larized — yellow or brown with iodine and sulphuric acid. The 
next layer consists of cork, but is seldom homogeneous (as in 
C. Convolvulacearum) and usually finely granular ; it is formed 
of thin, closely packed, round or angular rods, and in 
C. candidus is the thickest layer. In all other species except 
C. sibiricus it is very thin, and is completely wanting in 
C Portidacae , C. A mar ant ace arum and C. Bliti . The third 
layer is the cellulose-like layer. It is most strongly 
developed in C. sibiricus and C. Convolvulacearum. In 
C. candidus it forms its thick upper ridges without spread- 
ing out into an unbroken layer, and in C. cubicus , C. Lepigoni 
and C. Bliti it only forms the inner part of the projecting 
ridges and warts. 
Outside this cellulose layer is a fourth (or third) thin, 
commonly dark brown cuticularized layer. There is no 
distinct line of demarcation between this and the other 
cellulose layer however, and it appears to be merely the 
cuticularized outer portion of the latter. 
