Sept. 15, I9IS Soil Protozoa 531 



were developed; one large form was developed from moist soil in dried- 

 blood extract on the eighth day; thereafter no forms were recognized 

 until the twenty-third and twenty-fourth day, when a few small forms 

 were noted. Protozoan cysts were very numerous in the former part 

 of the experiment, but they gradually disappeared until very few were 

 seen after the twenty-second day, thus indicating that in culture solutions 

 some of the protozoa do not encyst after they have once become active, 

 but either die or are destroyed by other forms. 



SUMMARY OF PART II 



Under the conditions of the experiment and with the soils examined 

 it was found that : 



(i) In culture solutions the maximum development of small and large 

 ciliates and flagellates varies with the culture solution and the condition 

 and amounts of soil used for inoculation. 



(2) In dried-blood extract the maximum development of all ciliates 

 and flagellates is from the third to the fourth day, while in soil extract 

 it is from the second to the fifteenth day, depending upon the character 

 and amount of soil used for inoculation. 



(3) When the maximum development of all organisms is reached, 

 there is a gradual decrease in numbers until very few active forms are 

 present. 



(4) The greatest numbers of protozoa developed sooner in culture 

 solutions inoculated with the largest quantities of soil. 



(5) Per gram of soil, there is the greatest development from the least 

 amount of soil used for inoculations. 



(6) For the development of all forms soil extract seemed to be a little 

 more favorable than dried-blood extract. 



(7) The flagellates are the first organisms to excyst. 



(8) Very few large and small ciliates developed as compared with the 

 numbers of flagellates. 



(9) Drying the soil slightly favored the development of flagellates in 

 soil extract, while with dried blood there was little difference. 



(10) More large and small ciliates developed from the less composted 

 soils. 



(11) In dried blood more flagellates developed from the more heavily 

 manured soils. 



(12) Very many different types of ciliates were present, while the types 

 and numbers of amoebae were few. 



III.— PROTOZOA OF FIELD AND GREENHOUSE SOILS 

 INTRODUCTION 



The work reported in Part II of this paper on the protozoa of green- 

 house soils led the writer to make a more complete investigation of the 

 development of these organisms in culture solutions. In earlier experi- 



