610 Annals of the South African Museum. 



replaced or masked by Haematochrome. Colonies containing ripe 

 oospores present a very beautiful appearance macroscopically placed 

 in a small glass tube and held up to the light so that the sunlight is 

 reflected off the rapidly moving spheroids, those with ripe oospores 

 appear bright golden red among the bright green of the other colonies. 

 The oospore contains large food reserves, chiefly of starch in the 

 outer layers, volutin and fatty substances in the inner. Sections show 

 the large central nucleus connected by a network of protoplasmic 

 strands with the outer layers of the cytoplasm occupied by the 

 massive chloroplast and the numerous pyrenoids. 



Size and Appearance of the Oospore in the Two Species. 



The above general account applies equally to both F. Rousseletii 

 and V. capensis, but the mature oospores in the two differ considerably 

 in appearance. In F. Rousseletii the spines are usually longer, rather 

 more slender and sharply pointed, and with rather more tendency to 

 hooked ends than in V. capensis. The limits of size, including spines, 

 is much the same in the two species; if anything, the oospore of 

 F. capensis is rather larger than that of F. Rousseletii (F. capensis 

 49 to 62 IJL, V. Rousseletii 46 to 58 /x), so that when allowance is made 

 for the greater length of the spines in the latter the actual spore, the 

 part contained within the mesospore, is a good deal greater in 

 F. capensis (F. capensis 40 to 49 /x, F. Rousseletii 35 to 43 /x). 



The differences in appearance and structure, difficult to define in 

 words, are well brought out in the photographs of separate spores and 

 spores in situ shown in figs. E, F, Plate XV, and figs. C, E, Plate XXI. 

 They are mainly differences of degree ; length and shape of the spines 

 may vary considerably within one colony, but whereas in F. Rous- 

 seletii they vary about the type shown in fig. C, Plate XXI, in F. capensis 

 they vary about the type of fig. F, Plate XV. One spore of F. 

 Rousseletii may, for instance, have less well-developed spines than its 

 neighbours, and consequently approach the capensis type, but on the 

 whole the appearance is quite distinctive. 



In F. capensis, even at the height of its development, there are 

 rarely found a very large number of colonies containing ripe oospores, 

 whereas in F. Rousseletii during sexual activity a very great pro- 

 portion of red colonies, i.e. females with ripe oospores, may be found. 

 It would appear that in F. capensis the ripening oospores are not 

 retained so long within the colony as in F. Rousseletii, that very soon 

 after the colour has changed the colonies disintegrate and the ripening 



