46 



JAMES M. SHERMAN 



1/100 dilution, showing that this organism was probably active 

 in the soil containing this high amount of water. 



To obtain more definite data on this point, with known organ- 

 isms, an experiment was performed in which pots of sterihzed 

 soil were inoculated with animal-pure cultures of three of the 

 types of flagellates mentioned in the first part of this paper. 

 The pots were inoculated with 0.1 gm. each of soil cultures of 

 the respective organisms per 1,000 grams of sterile soil. The 

 water content was then held at 15 per cent (a little below normal 

 for a soil of this type). Determinations for protozoa were made 

 immediately after inoculation, and then at intervals for fifteen 

 days. The results obtained are given in Table III. 



TABLE ni 

 The multiplication of three types of protozoa in soil. (H^O content 15 per cent.) 



ORGANISM 



Monas (sp). 

 D. radiata. . 

 Flagellate A 



NUMBER PER ORAM 



Start 



1 



1 



10 



days 9 days 12 days 15 days 



10 

 100 

 100 



10 



100 



1,000 



1,000 



1,000 



10,000 



10,000 

 100,000 

 100,000 



In similar tests using Colpoda cucullus, Balantiophorus elongatus 

 and Oxytricha sp. no multiplication could be detected during 

 a period of thirty days. These results appear to substantiate 

 the data of Goodey on the ciliates. 



A point which probably deserves mention in this connection, 

 is that when sterilized soil is inoculated with normal soil, the 

 protozoan fauna rises in numbers above that of normal soil, 

 just as does the bacterial flora. In other words, it is probable 

 that the micro-organic balance remains about the same. In 

 Table IV are given the results obtained on five pots of sterilized 

 soil which were inoculated with normal soil. 



Higher dilutions have not been tried, but it is not unlikely 

 that under such conditions the number of protozoa may reach 

 1,000,000 per gram. This fact is not of great significance, but it 

 has a practical application in indicating that the subsequent 

 work on the relation of the soil protozoa to the bacterial flora 



