302 Wager. — On the Structure and 
when sown in water the large spherical spores of C. Portidacae 
germinate in six to ten hours, but he had never seen the 
other spores germinate, and once only had he observed 
a spore of C. candidus to germinate. In germination a fila- 
ment of uniform diameter is developed. 
Hoffman (’59) supported Tulasne’s observations on the 
development of the sporangia, and stated that he believed 
he had seen the direct germination of spores of Cystopus^ 
and was unable to accept the account given by Prevost. 
De Bary (’60) confirmed Prevost’s observations by observa- 
tions on C. candidus and C. cubicus , and pointed out that the 
spores are really sporangia and produce in C. candidus from 
five to eight spores, and in C. cubicus from eight to twelve. 
He was not able to confirm Tulasne’s observations as to the 
direct germination of the spores. 
De Bary’s larger memoir, which has already been quoted, 
appeared in 1863 , in which the sexual organs were for the 
first time described. 
Cornu (72) in his Monograph on the Saprolegnieae referred 
to the growth of the cell-wall in Cystopus , and pointed out that 
at first the membrane of the oospore is thin and the contour 
perfectly regular. Later it is composed of a thin exospore 
and a thick endospore, and by examination of oospores of 
different ages it is seen that the external diameter increases 
in size while the internal one diminishes. There is, therefore, 
growth in two directions, centrifugal and centripetal. He 
objects to De Bary’s observation that the epispore is formed 
from the periplasm, and points out that he has omitted to 
note the decrease in the internal diameter of the spore, which 
is even more easily seen than the increase in the external 
diameter. Pic regards it as more logical and more con- 
formable with what is known as to the growth of cell-wall 
in other cases, to admit that the oospore formed at the 
expense of a part of the cellular protoplasm should be 
nourished afterwards by the remainder which it first of all 
absorbs. He very pertinently asks why, if the periplasm 
has the power of secreting a wall without being elaborated 
