mo 



soli. I'lioTo/.OA IX SOUTII AKKICA. 



Influence of Depth of Soil. 



For this pur|)ose, a compact block of soil, twelve inches 

 deep, was divided into twelve slabs, each slab or layer being one 

 inch in depth, great care being taken to avoid any mixing of the 

 layers. The soil was from the Eosebank Experimental Station 

 (Liesbeek alluvial), and its protozoal content, as shown in cultures 

 of each layer, is given on pp. B42-4. A composite sample was also 

 examined. A summary of the organisms at each depth is given 

 in tabular form (Table II), each successive inch layer being 

 numbered 1 to 12 and the composite sample being numbered 13. 



Table IT. 

 LiBSBEKK Soils. 



From the table it will bs seen that two organisms only, 

 Euglijpha sp. and Oikomonas termo, persist throughout the series, 

 though Pleuromonas jaculans is present in all but the surface 

 layer of soil, and is present as deep as 12 inches from the surface 

 of the ground. Amorha Umax, Bodo (P.) parva. Holophrya avion, 

 Cyclidium glaucoma, Lacrymaria olor and VoriiccUa campanula 

 can persist in many layers of soil to about twelvf 

 inches deep. The rarest ciliate seen, Prorodon ovum, occurred 



