Sept. 15. igis Soil Protozoa 557 



SUMMARY OF P.ART IV 



Under the experimental conditions described above it has been found 

 that: 



(i) A temperature of 15° to 16° C. is the most favorable for the devel- 

 opment of small ciliates. 



(2) At 15° to 16° hay infusion is the most favorable culture solution 

 for the development of small ciliates. 



(3) The maximum numbers of small ciliates are developed at an ear- 

 lier period in dried blood than in hay infusion. 



(4) The maximum development of small ciliates at 6° to 7° varies 

 from 17 to 30 days after inoculation. 



(5) At 15° to 16° the maximum development of small ciliates occurs 

 from seventh to twenty-fifth day after inoculation. 



(6) The small ciliates develop sooner at the higher than at the lower 

 temperatures. 



(7) The lower temperatures retard the development of small ciliates. 



(8) Dried-blood extract and hay infusion are unfavorable media for 

 the development of large ciliates. 



(9) Large ciliates will develop at all the temperatures noted if condi- 

 tions are favorable. 



(10) Many flagellates developed at all temperatures noted. 



(11) The maximum development of flagellates occurs at 6° to 7° in 

 dried-blood extract and at 15° to 16° in hay infusion. 



(12) Hay infusion is the most favorable medium for the development 

 of maximum numbers of flagellates. 



(13) The higher temperatures encourage early development of flagel- 

 lates, while lowest temperatures retard their development. 



(14) At all temperatures the flagellates develop sooner than the 

 ciliates. 



(15) At 15° to 16° the flagellates appear four or five days before the 

 ciliates. ^ 



(16) As soon as the maximum development is reached there is a 

 gradual decrease in the numbers of all forms of protozoa. 



(17) Species of Colpoda, Vorticella, Prorodon, and Glaucoma develop 

 at 15° to 16°, at 22° to 23°, and at 29° to 30°. 



(18) A few individuals of Colpoda and Paramecium develop at 6° to 7°. 



(19) At 15° to 16° C. Colpoda is the most numerous ciUated form. 



(20) The temperature of 29° to 30° is very favorable for the develop- 

 ment of species of Colpoda, Prorodon, and Glaucoma. 



(21) Some ciliates die when conditions become unfavorable. 



(22) Vorticella cysts are present in field soils which have received 

 applications of manure. 



(23) Hay infusion and dried-blood extract are unfavorable media for 

 the development of amoebae. 



