Sept. IS. 1915 Soil Protozoa 533 



In this study the same classification of protozoa was made as in 

 previous experiments. The small ciliates included all organisms from 

 the smaller to and including Colpidium colpoda. The vorticellae were 

 also included. The large ciliates included all forms larger than Col- 

 pidium colpoda. The flagellates included all forms of flagellates that 

 were observed. 



DEVELOPMENT OF PROTOZOA IN CULTURE SOLUTIONS INOCULATED WITH 

 VARIOUS AMOUNTS OF SOIL 



DEVELOPMENT OF SMALL CILIATES 



From Table IX it is apparent that the development of small ciliates 

 varies greatly with the kind of media and soil used. It is noted that 

 but few of these organisms developed in any of the solutions of dried- 

 blood extract inoculated with the varying quantities of field soil. Very 

 many appeared from the 5-gm. and 20-gm. inoculations of the same soil 

 in hay infusion, indicating that only definite types develop under certain 

 conditions. That this is true is again apparent. In hay infusion inocu- 

 lated with 100 gm. of field soil only a few organisms developed on the 

 second and third days. In the i-gm. and 50-gm. inoculations no small 

 ciliates had developed during the whole period of 30 days, but in the case 

 where 100 c. c. of hay infusion had been inoculated with 5 gm. of soil, 

 as many as 30,700,000 organisms per gram were present on the eighth 

 day. With the 20-gm. inoculations 3,700,000 had appeared on the ninth 

 day. In both media more small ciliates developed from the compost 

 than from the field soil. In the compost inoculations of both dried blood 

 and hay infusion a few organisms appeared on the second day where the 

 largest quantities of soil had been used. But the maximum numbers 

 were not reached until the fourth day with the former and the fifth day 

 with the latter solution. In the development of the maximum numbers 

 of small ciliates in the diflferent culture solutions, a variation in the period 

 of the development was very apparent. In all inoculations of dried blood 

 the greatest numbers were noted on the third and fourth days. With 

 hay infusion the maximum numbers did not appear until the fifth, and 

 in some cases not until the eighth day, depending upon the amount of 

 soil used for inoculation. 



DEVELOPMENT OP LARGE CILIATES 



No large ciliates were noted in any of the inoculations of the field soil, 

 indicating that either the conditions in the media must have been un- 

 favorable for their development or that there were no cysts of large 

 ciliates in the soil. 



That such cysts are present in greenhouse soil is indicated by the 

 development of these organisms in both dried blood and hay infusion. 

 The former solution, however, did not seem to be very favorable for their 



