An Investigation of a Species of Saprolegnia. 31 7 
frequently produced when resting sporocysts on an old culture on 
egg, were transferred to water-cultures. 
9. Aplanes-type. In a hanging drop culture two days old on the 
skin of fish in water, small sporocysts were observed at the ends of 
hyphse which seemed to be normal in appearance. They were kept 
under observation, to watch the discharge of spores, but in this case 
it never took place. They seemed quite ready, but no motion of 
the spores could be seen within the sporocyst and each appeared 
very clearly defined and spherical (Fig. 33). The slide was kept 
under the microscope till next morning, when the spores were found 
to have germinated directly while still in the sporocyst, so that the 
spores had never passed through any motile stage (Fig. 32). This 
feature is characteristic of the genus A planes. On the same culture 
sporocysts were observed discharging motile zoospores in the 
normal manner. 
% 
Although all the conditions found in these investigations may 
be directly due to the method of culture or to the sudden change 
from one medium to another, it shows how very variable this 
species is and how easily it can alter the form and method of 
discharge of the sporocyst. It is moreover a remarkable fact that 
the characteristics of six genera can be obtained from one pure stock 
culture. The results have been so very variable on several points 
that it is almost impossible to say whether this species should be 
attributed to the genus Saprolegnia or to Achlya. The following 
characters common to these two genera have been observed in the 
present species:— (a) discharge of motile zoospores ; ( b ) encystment 
of zoospores; (c) second motile stage; ( d ) formation of gemmae; 
(e) formation of multiple sporocysts; (/) formation of dictyo- 
sporocysts. 
On the assumption that the first-formed sporocyst on a new 
mycelium will be more likely to represent the typical form for the 
species, the balance is in favour of the genus Saprolegnia , as the 
first-formed sporocysts were nearly always found to discharge 
actively motile zoospores which showed a definite swarm-period 
lasting for several minutes. 
In spite of the trial of a great variety of media and of the 
various culture solutions recommended by Kauffman as being a 
means of inducing the formation of sexual organs, no signs of the 
formation of any form of sexual organs has so far been found— 
that is during a period of culture extending over four months. 
