616 Annals of the South African Museum. 



vlei water for six months in a similar place to that in which the oospore 

 stock jar stood, i.e. in a south window, where no direct sunlight ever 

 fell. Other algae in the water flourished, but the Volvox oospores, 

 though quite healthy, showed no signs of germination. Also the 

 oospores in the stock bottle were in water, yet did not germinate. 



2. Complete drying is not essential, but is beneficial. Oospores 

 transferred direct from the stock bottle to the culture germinated 

 in a few cases, but more oospores germinated if the material containing 

 them had been completely dried, even if for a short time only, before 

 being placed in culture. In one case oospores from the stock dish 

 were put in a small dish and allowed to dry completely. The following 

 day, 4th August 1931, water was added and the whole placed in the 

 sun. The two succeeding days were wet and overcast, but were 

 followed by two warm, sunny days ; on 9th August the material con- 

 tained many Juveniles, some free in the water, others still contained 

 in the surrounding vesicle. 



3. The oospores are not necessarily fully mature when liberated 

 by the break up of the parent colony. In F. capensis, at any rate, 

 they appear to need a further period in water before drying completely. 

 In November 1931 colonies of F. capensis from Belvedere Road 

 containing apparently ripe oospores, including one which was liber- 

 ating the oospores by disintegrating (see p. 611), were placed on slides 

 and allowed to dry. Two months later culture experiments were 

 started, but all the oospores, most of which had remained bright 

 red-gold in colour, disintegrated ; a very few only which had turned 

 dark golden brown showed early stages in germination, but developed 

 no further. So far the oospores of F. capensis have not been success- 

 fully germinated, but everything points to the process there following 

 exactly the same lines as in F. Roitsseletii. 



Germination of the Oospore. 



The successive steps in germination are as follows : 

 Stage 1. The spiny epispore cracks and the spore enclosed in 

 meso- and endo-spore either escapes into the water (Plate XL VI, 

 B-F) to continue development free in the water, or more rarely 

 remains more or less enclosed in the cracked epispore, developing 

 within it (Plate XL VI, H). 



On escape the spore consists of a deep golden-brown spore-body 

 (protoplast), in the centre of which careful focussing sometimes 

 reveals a single large nucleus, enclosed in a delicate limiting membrane 



