114 Mrtliotls for E.rdlllllHttioil of' Sni/ I'rutiiZon 



succession of animal forms. By selecting the time and method of 

 culture it will probably be found possible to get pure animal cultures 

 of any of these forms. 



The question how far the dominant active forms in a soil are repre- 

 sented in the cultures depends largely, firstly, on the condition of the 

 soil, and, secondly, on the condition of the cultures. We return to 

 this question below, but it may be pointed out here that in the case of 

 most soils the conditions on the cultures mentioned above seem rather 

 rich for some members of the active fauna, with the result that these 

 forms appear very late in the cultures. A certain check can be obtained 

 on these results by means of cultures in which a small amount of water 

 is added to the soil. 



III. Some Eesult.s. 



So far the soils which have been examined by the methods described 

 above are relatively few in number, but of varied types. 



In three cases, where the soil was taken respectively from a cucumber 

 border, from a fertile garden plot, and from the site of an old manure 

 heap, the soils were probably far richer in farmyard manure than even 

 the most richly manured fields; and correlated with this there was a 

 higher capacity for holding water. As would be e.xpected, all the indi- 

 cations were that these soils supported a far denser protozoan fauna 

 than was found in the poorer soils examined. 



In the cucumber border, tlie dominant protozoa were iimoebae — 

 one of the limax type (VaJilkampfia soli n. sp.) and one of tlio ianielii- 

 podian type {A. cuciimis n. sp.). Thecamoebae. notably a species of 

 Euglypha and a Trinema, could be detected in live films, though they 

 were fairly rare on the fixed films, and were probably the next most 

 numerous protozoa. Flagellates and ciliates were present only in small 

 numbers. 



The garden soil, and the soil taken from the site of an old manure 

 heap (both at Abergavenny), contained numy amoebae, but a great 

 preponderance of thecamoeban forms. The similarity between their 

 fauna is probably not accidental; it is very likely that the dominance 

 of the thecamoebae in the garden soil was a persistence of the dominance 

 of these protozoa in the manure heap with which the garden had been 

 enriched. 



In culture these thecamoebae did not appear in considerahle numbers 

 until two or three weeks at least after the culture had been started. 



