Volvox in South Africa. 615 



dried on the slide and material transferred direct from the stock 

 bottle (i.e. without previous drying) were used : 



(1) Oospores placed in tank- water * and kept indoors. 



(2) Oospores placed in tank-water and placed outside in the sun. 



(3) Oospores placed in water obtained from Volvox vleis and 

 strained, placed in the sun. 



(4) Oospores placed in pond-water plus a small quantity of culture 

 solution (Uspenski and Uspenskaja, 1925, p. 397). 



To prevent overheating and to reproduce as far as possible the 

 conditions of lighting obtaining in the natural habitat, the small 

 glass culture-dishes (2 to 4 inches in diameter, about 2 inches deep, 

 wide open at the top) were sunk in a layer of garden soil in a large 

 basin of water and the whole placed in a spot where the morning sun 

 falls but which by noon is in shade. 



From these four experiments the following results were obtained : 



No. 1 was practically barren of results ; a few eggs hatched out 

 from their outer spiny coats, but did not develop further. 



Of the three placed in sunlight, all yielded some Juveniles essen- 

 tially similar to those collected on the Cape Flats, i.e. some at any 

 rate of the oospores germinated completely. 



In No. 2 no further stages were seen, but in Nos. 3 and 4 develop- 

 ment continued to the second generation, possibly further. 



The addition of small quantities of the culture solution was bene- 

 ficial, but the use of the full strength solution did not give good results, 

 causing pathological phenomena in the developing colonies. 



For observation of the stages in germination the most convenient 

 method on the whole was the placing of oospore material on slides 

 and allowing it to dry out completely, subsequently immersing the 

 whole slide in the culture medium. For observation the slide was 

 lifted out and the material examined without disturbing it with 

 care cover-glasses can be used and later removed without injuring 

 the material on the slide. 



Although the culture experiments were aimed primarily at obtaining 

 good germination stages and not at studying the conditions necessary 

 for germination and were therefore not at all exactly carried out, 

 the following facts emerged : 



1. Direct sunlight is necessary for the germination of the oospores. 

 Two years previously oospores of V. capensis were kept in a jar of 



* The tank is filled by rain-water from the house-roof. Since Cape Town's 

 ordinary water-supply is chlorinated before distribution from the reservoirs it 

 is best to avoid using it in culture experiments. 



