530 A matin of tlte Smith African Museum. 



comparative investigation of the mode of septum-formation in the 

 two species would be of much interest. 



The material of S.africana provided numerous oogonia, both unfer- 

 tilised and fertilised, and what were probably antheridia. The oogonia, 

 like the vegetative " cells," are of very diverse length, and either 

 occurred singly or in short series. In general they are characterised 

 by the formation of a very large number of oospheres ; in the case 

 shown in Fig. 10, A there were 155 female cells present, and it is not 

 unlikely that this number may be exceeded. On the other hand, 

 oogonia are also to be found witli a relatively small number of 

 oospheres. In such cases the latter are arranged in a single or double 

 row, whilst, when numerous, the oospheres are in great part very 

 closely packed and may form a number of irregular longitudinal series 

 (Fig. 10, A). Sometimes they are polygonal through mutual pressure, 

 but mostly they are rpiite spherical. As a general rule, the entire 

 protoplast is used up in the production of the oospheres (as in 

 Fig. 10, A), but occasionally a small shrunken mass of protoplasm 

 remains. One or more central pyrenoids could be detected within the 

 oospheres. The latter are relatively constant in diameter (18-21 jj.), 

 though in the large oogonia smaller oospheres are always to be found. 

 The apertures formed in the oogonial wall are not numerous, and are 

 small and often ill-defined ; they frequently show an irregular edge, 

 and commonly, at least, are not circular, but wider in the transverse 

 than in the longitudinal direction (e.q in one case 4" 5 x /i) 

 (Fig. 10, C,D,ap.). 



Either in the same or in different filaments there occurred cells 

 with dense, fine, granular contents, and provided with apertures 

 similar to those of the oogonia. It is very likely that these represent 

 the antheridia. Numerous small spindle-shaped bodies, observed in 

 some of these cells, may have been spermatozoids, but the cells in 

 question were not sufficiently well preserved to make sure of this 

 point. 



It appears that, after fertilisation, the oospore becomes clothed by a 

 thin membrane which fits closely round the contents. Within this 

 the development of the membrane of the mature oospore takes place 

 (Fig. 10, B, d 1 ), and, when the latter is completed, the first-formed 

 membrane is ruptured and cast off ; in some of the oogonia such 

 empty primary membranes could be recognised in the neighbourhood 

 of almost every oospore. 



The oospores are as closely packed as the oospheres (cf. Fig. 10, G). 

 The contents are spherical or commonly oval (Fig. 10, B) and include 

 from one to three pyrenoids. They exhibited no special coloration, but 



