Volvox in South Africa. 535 



very dark greeii bodies can in many cases be seen. Usually the axis 

 lies somewhat obliquely during movement, due probably to the 

 greater weight of the posterior half. In the larger colonies the 

 arrangement of the daughter colonies in two planes may sometimes 

 be made out. Other colonies appear bright reddish orange these 

 contain maturing oospores, the red colour of which masks the green 

 of the vegetative cells. Such reddish colonies, when present, are 

 very conspicuous among the predominating green of the majority. 

 Among the latter closer inspection can differentiate various types, 

 besides those containing daughter colonies. Some are darker green 

 and very finely punctate; these are young female colonies whose 

 eggs have not yet changed colour. Others are lighter in colour than 

 the asexual colonies, and they too appear finely punctate except at 

 the anterior end these are male colonies with sperm globoids, which 

 are visible among the vegetative cells owing to their greater density 

 and size, not from stronger colouring as in the case of the eggs. 

 Finally, large, clear, nearly colourless colonies may also be seen 

 asexual colonies from which all the daughter colonies have escaped, 

 or mature male colonies in which few or no sperm globoids remain. 

 Both may continue moving slowly among the younger colonies for 

 some time after the loss of the reproductive bodies, whether asexual 

 daughters or male globoids, before finally degenerating. 



Movement. 



With the assistance of a good hand lens the movement of the 

 coenobia may be seen to be twofold, a rotation on the polar axis 

 and a movement forward in the direction of the anterior pole, which 

 is in general directed towards the light. In addition to the colonies 

 which are actively moving, it is usually possible to see others in which 

 the voluntary movement has ceased, and which are as a consequence 

 slowly dropping downwards through the water, the heavier posterior 

 end always lowest. 



The rotation on the axis is not always in the same sense. In 

 favourable material, the majority of the coenobia can be seen to be 

 rotating in a clockwise, others in a counter-clockwise, direction. If 

 one colony be singled out for observation, it may often be seen to 

 pause momentarily in the rotatory movement and to resume in the 

 opposite sense. Janet (1912, p. 133) and Klein (1889, p. 168) 

 observed the same behaviour in the case of the European V. globator. 



If active material be placed in a watch-glass with plenty of water 



