Volvox in South Africa. 613 



quantities of very minute green motile bodies individually only just 

 visible to the naked eye, but fairly clear in bulk. Examined micro- 

 scopically, the collection was found to contain, in addition to typical 

 Flats Volvox in young stages (some with inverting daughters) and a 

 great deal of very beautiful Eudorina, a third type of motile green 

 spheroid, which was at first sight taken for a new species of Volvox 

 with very few large cells (Plate XLIX, A). But in these tiny spheroids 

 were one or occasionally two (very rarely three) well-developed 

 daughter colonies of the same type and very nearly as large as those 

 found in typical colonies of V. capensis ; one of the larger of these 

 small colonies measured 284 x 292 JJL, and contained a single large 

 daughter, 151 x 155 /z, rotating within it. Hence it was concluded 

 that these beautiful little spheroids were the product of the germina- 

 tion of oospores of V. capensis. 



These " Juvenile " forms are always small, composed of 256 to 

 512 cells or thereabouts, the component cells being very much larger 

 and more widely spaced than in the adult form, but otherwise similar 

 (Plate XLVIII, E, F). A more detailed description of the Juvenile 

 is given below (p. 625). Later in the season similar Juveniles were 

 collected at Dabchick Vlei, and one or two were seen in preserved 

 material from Khodesia, while quite recently they have been collected 

 in enormous numbers in the case of V. Rousseletii at Kimberley. 



Although the evidence was strong that the supposition as to their 

 true nature was correct, it was most satisfactory to have it proved 

 beyond a doubt when ripe spores of the Eietfontein material were 

 obtained in masses and by suitable methods induced to germinate. 

 As a result, Juveniles of exactly the same type as those collected 

 from the Cape Flats were produced (Plate XL VII, H-L ; Plate 

 XLVIII, A-D). The results of these germination experiments were 

 extremely interesting, and proved to be what might be expected from 

 the study of the life-history of the nearest Volvox allies, Pleodorina, 

 Eudorina, etc., as revealed by the work of recent investigators such 

 as Hartmann (1918) and Schreiber (1925), but contrary to the pub- 

 lished accounts of the behaviour of Volrox. 



Development of Oospore subsequent to Liberation. 



Since at liberation the oospores, in some cases at any rate, are not 

 quite ripe, the process of maturation continues in the water and is 

 probably assisted by subsequent drying. Apparently temperature is 

 an important factor in the process. When fully ripe the oospore 



