526 Annals of the South African Museum. 



published, although the Cape Flats form has for some years past 

 been collected fairly regularly during the winter months. 



In February 1930 Mr. E. J. Steer succeeded in obtaining a rich 

 growth of Volvox from soil brought by Miss E. L. Stephens from 

 Eietfontein, near Johannesburg ; the culture was first made in a 

 small glass tank, later established in a large tub, whence it spread 

 to other tubs and fish-ponds in Mr. Steer's garden at Sea Point. It 

 has now continued to flourish in one or other of its chosen spots for 

 over two years, for a great part of which period it occurred in very 

 large quantities. Thus a continuous, unlimited supply of vigorous 

 living material became available, and it seemed a good opportunity 

 to carry out detailed observations on Volvox, in the hope, first, of 

 clearing up various points as regards the identity of the South African 

 species, and, secondly, of possibly adding to our knowledge of the 

 genus Volvox as a whole. At the same time a careful study of the 

 form of Volvox found in various vleis on the Cape Flats was started, 

 and its structure and behaviour compared with those of the Riet- 

 fontein material. This was made possible in the beginning by the 

 fact that, although the year 1930 was a very bad one for Volvox on 

 the Flats in general, yet in one locality (Scanlan's Vlei, Wetton 

 Road) Volvox was even more abundant than usual, while the following 

 year (1931) there was an exceptionally good and prolonged season 

 (May to November) for Volvox in most of the localities near Cape Town 

 in which it is known to occur. 



Aim of the Investigation. 



The aim of the investigation, then, is twofold : 



(1) To carry on a detailed observation of two of the forms of 

 Volvox found in South Africa Volvox Rousseletii West, as it appeared 

 in cultures of soil from Rietfontein, and Volvox capensis Rich and 

 Pocock (1932, p. 462), from the Cape Flats more or less on the lines 

 followed by Klein (1889 a and b, 1890), Janet (1912, 1922, 1923), and 

 other workers in the case of T 7 . globator and V. aureus in Europe, 

 supplementing microscopic observation of the living organism with 

 observations carried on in the field, and more detailed observation 

 of prepared sections of carefully fixed material ; and 



(2) To supplement, if possible, the facts already known as to the 

 life-history and structural details of Volvox in general. 



