Sept. IS, 191S Soil Protozoa 553 



DEVELOPMENT OF SOIL PROTOZOA AT DIFFERENT TEMPERATURES 



From the data presented it is seen that the maximum number of 

 small ciliates in the dried-blood extract were found at 15° to 16° C, 

 while the greatest number of flagellates appeared at 6° to 7° C. In 

 hay infusion the flagellates developed in greater numbers at 15° to 16°. 

 In some solutions of hay infusion the small ciliates developed at 15° to 

 16° and in others at 29° to 30° C. 



That the ciliates were directly detrimental to the development of 

 flagellates can not be definitely stated at this time, but it is noted that 

 in solutions of culture media incubated at 6° to 7° C, where very few 

 ciliates developed when the flagellates had excysted, many more were 

 present until the end of the experiment than had been noticed in any 

 other inoculations. In view of this fact the flagellate development 

 might be influenced by the presence of ciliates. At 6° to 7° C. the 

 maximum number of flagellates appeared from 7 to 17 days before 

 the maximum ciliate development was reached. At this temperature 

 in no case was the maximum ciliate development noted until the tenth 

 or eleventh day, while the greatest ciliate development appeared from 

 the seventeenth to the twenty-seventh day after inoculation. In all 

 inoculations of hay infusion at 6° to 7° the maximum number of flag- 

 ellates developed at an earlier period than did the ciliates. The maxi- 

 mum development of the former occurred from the twenty-first to the 

 twenty-ninth day, while that of the latter was 30 days after inocula- 

 tion. In all inoculations at 15° to 16° the 'maximum development of 

 small ciliates and flagellates was reached sooner than at the tempera- 

 ture of 6° to 7° C. This period varied from 2 to 20 days. In compar- 

 ing the maximum numbers of small ciliates and flagellates developed at 

 22° to 23° wdth those developed at 15° to 16° it is seen that, with two 

 exceptions, the greatest development was reached earlier at 22° to 23° C. 

 Comparing the development at 22° to 23° with that at 29° to 30°, it 

 is seen that there was no uniformity; in some cases the maximum was 

 reached sooner at the former, while in others it occurred at the latter 

 temperature. As in previous experiments, when the maximum devel- 

 opment was reached, the numbers of protozoa gradually decreased, 

 showing that the conditions for continuous multiplication became unfa- 

 vorable. 



Table XII shows the variation in the rate of multiplication of the 

 protozoa in the different solutions from their first api^earance until 

 the first increase was noted. This increase was usually the first day 

 after their presence was noted. There is a marked difference in the 

 rate of multiplication of each type in each solution at every different 

 temperature employed. No correlation is noted between the multi- 

 plication of the small ciliates in like infusions inoculated with the same 

 soil incubated at different temperatures. The same statement holds 

 true for the multiplication of the flagellates and large ciliates. In like 



