370 soil protozoa in south africa. 



Summary. 



(1) 1x1 continuation of our previous work, examinations have 

 been made of more South African soils from the Cape Province; 

 Transvaal and Orange Free State. Some soils from the south of 

 Portuguese East Africa have also been examined. Direct exami- 

 nations and water cultures have been used throughout. The list 

 of genera and species of Protozoa recorded from soils in our 

 previous communication has been extended. 



A HcrjicfoDionas, named H. terricola'. (see p. 344), was 

 found in samples of soil from Rosebank (Liesbeek), C.P., from 

 infertile patches at Glen, and from the Observatory Garden at 

 Lourengo Marques. 



(2) The geographical distribution of the different genera and 

 species of Protozoa of the soils examined by us has been extended 

 (see p. 35.5), and a list of the trophic Protozoa found by direct 

 examination in waterlogged soils by us is appended (see p. 358). 



(3) Compared with our results of last year, an increase in the 

 number of genera and species of Protozoa in waterlogged soils has 

 been observed. 



(4) Study of the influence of various environmental effects 

 has been continued. Interesting results were obtained in regard 

 to the influence of the depth of soil fvn the numbers and nature of 

 the Protozoa contained therein. A block of soil from the surface 

 to twelve inches deep, cultured in successive inch layer samples, 

 had Euglypha sp. and Oikomonas termo as the only organisms 

 found in each layer of the series. A soil Herpetomo)ws was found 

 in the layer of soil taken at ten inches deep. In cultures of 

 relatively deep soil, cysts and trophic forms of Euglcna viridis and 

 E. oxyuris were found. 



Cultures of virgin and cultivated Karroo soil, taken at six and 

 nine inches deep, showed differences in nuinbers of both organisms 

 and genera. These Karroo soils compared with one another and 

 with Liesbeek soil taken at six inches deep showed that three 

 Flagellates and one Ciliate were common to each soil. The 

 other Protozoa showed divergence. The same three soils, taken 

 at nine inches deep, contained one thecamoeba, three Flagellates 

 and one Ciliate in common, but these orgiinisms common to each 

 soil were almost entirely different from those common to the same 

 soils taken at six inches deep (see Tables III, IV). 



The culture area exposed appears to influence the number of 

 trophic Protozoa detected, shallow cultures yielding more 

 organisms than deeper ones (see p. 363). 



Darkness and light appeared to have little influence on the 

 rate of development of Protozoa in our cultures, except that 

 Hyalosphcnia eJcgans appeared to react to the sudden application 

 of light. 



The distribution of the Protozoa in the cidture fluid was . 

 investigated. A few typical examples only are cited, and it is 

 considered that in order to obtain a true estimate of the protozoal 

 population of a culture it is necessary for the sample to include 

 some of the surface filrn, middle layer and soil layer of culture 

 fluid (see p. 364). 



