Methods of Reproduction in the Saprolegniacece. 187 
Sometimes a series of cylindrical oospores is formed, derived 
from the development of a chain gemma. In this case almost 
invariably one of the segments shows the presence of a protuberance 
or germ tube (p. 186, figs. 6, 13 and 14). 
Occasionally one of the masses in such an oocyst is seen to 
remain granular in appearance, with a delicate membrane, while 
all the others have formed the usual thick exposures (p. 186, fig. 12). 
No further development of these bodies has been noted, and no 
case of germination of the oospores kept for two months in various 
cultures has yet been observed. 
Frequently in the cultures very small oocysts were found, only 
containing one oospore; these are derived from specially small 
gemma-like bodies (p. 186, figs. 9 and 10). Sometimes these small 
oocysts are multiple, and each contains one oospore (p. 186, fig. 8). 
The Typical Oocysts. Besides the somewhat abnormal cases 
just described, oocysts of the ordinary type were found in great 
abundance. Their occurrence is first noted after about nine days, 
and on some of the older cultures, after fourteen days’ growth, they 
were produced in such abundance that the whole mycelium had the 
appearance of being densely covered with minute spots. 
The oocysts are borne singly and terminally on lateral branches 
of the main hyphae, or on short hyphje arising from the base of the 
mycelium ; they are spherical or pear-shaped, and remain firmly 
attached to the hypha which bears them. 
The wall of the oocyst is fairly thin and not deeply coloured, 
usually quite free from spots, but some show the presence of a few 
ill-defined patches on the wall. No case has been observed where 
the spots are clearly defined or occur as distinct coloured patches. 
The Oospores. The number of oospores produced varies to 
some extent. The usual number appears to be eight in the typical 
form of oocyst, but frequently as many as twelve are found, and 
sometimes only six. Reference has already been made to the 
occurrence of single oospores. 
The size of the oospores also varies greatly, 20/x—30/x, but the 
average for typical oocysts is 22/x. 
In the cylindrical form of oocyst, the diameter of the larger 
oospores is 27/x, average size. The presence of the specially small 
oospores may be considered abnormal and of only rare occurrence. 
The oospores are usually spherical, but occasionally oval in the 
narrow oocysts. They have a clearly defined, perfectly smooth, 
brown coloured outer membrane or exospore, and a thinner 
