SOIL PROTOZOA IN SOUTH AFRICA. 37-S- 



tion. The seed produced by glox. pollen on a hybrid plant differed 

 markedly in shape (see bottom two figures) from the seed formed 

 with luted pollen on the same, identical hybrid plant. Drawn to 

 scale. 



Fig. 2. — Typical leaves of the various generations; taken of 

 the same length, and showing the differences in the mean widths, 

 indentations and general veining. 



Typical flowers of the same generations, showing the differences 

 in the shape of the calyx, and in the length, breadth, spotting and 

 marbling of the corolla. Drawn to scale. 



Plate V. 



Longitudinal sections of ovules and seeds; glox. fertilised with 

 lutea pollen. In all the figures, except in fig. 1, the power of 

 further growth had ceased. 



e. Embryo, end. Endosperm, i.e. Empty cells of nucellus. 

 e.s. Embryo-sac. f.t.l. Formation of tapetal layer. //. Nucellus. 

 p.o.ie. Persistent outer wall of testa cell. t .1 . Tapetal layer. 

 t.l.l. Tapetal layer still living, t.l.e.c. Hypertrophied tapetal layer 

 of empty cells. 



SOME PROTOZOA FOUND IN CERTAIN SOUTH AFRICAN 



SOILS.— 1. 



BY 



II. B. Fantham, M.A., D.Sc , and Esther Taylor, M.Sc, 



Department of Z<>oh><j//, University of the Witwatersrand, 

 Johannesburg. 



Head July 15, 1921. 



Introduction. 



The Protozoa are a large and important group of organisms, 

 which are widely distributed. Many inhabit fresh water, occurring 

 in ponds and ditches and in infusions exposed to the air. Some 

 Protozoa are marine. The parasitic Protozoa have been widely 

 studied in connection with various diseases in man and other 

 animals. Free-living Protozca inhabiting the soil have recently 

 received attention, and it is their relation to soil bacteria and the 

 possible bearing on soil fertility which has been chiefly investigated 

 by the few workers who have given direct attention to the subject. 



Russell and Hutchinson (1909, 1913), working at Rothamsted 

 Experimental Station, England, were among the first to consider 

 the relation of Protozoa to bacteria and to fertility, using the 

 method of partial sterilisation of the soil. Such partial sterilisa- 

 tion may be attained by heat, and by the addition of toluene or 

 carbon bisulphide to the soil. Partially sterilised soil was found 

 to be more productive than untreated soil, but the effects produced 



