166 



Mr. T. Goodey. A Contribution to our [May 19, 



abundant a day or two after the culture had been made. On the other 

 hand, cultures of treated soil failed to reveal these protozoa, which are 

 much more susceptible than the bacteria to the sterilising agents employed. 



These organisms included certain amoebae, flagellates, and infusorian 

 ciliates, known to be devourers of bacteria when living in a liquid medium. 



To these protozoa, therefore, the authors assign the function of limiting the 

 activity of bacteria in the soil, though they point out* that they by no means 

 wish to imply that they are the only limiting factor. 



Various workers have recorded the presence of protozoa in the soil,, 

 especially of amoebae. Greefff gives an account of four species of amoeba 

 which he found in association with damp earth and moss, etc. Beijerinck,$: 

 Celli,§ Frosch,|] Tsujitani^ describe certain small amoebae which they obtained 

 in cultures made from garden soil, and give methods for obtaining these 

 organisms in pure culture on various nutrient media of a solid nature. 

 Stormer** found that several colonies of amoebae developed in plates- 

 inoculated with 1 mgrm. of soil. 



Hiltnerff speaks of finding numerous amoebae, flagellates, and ciliated 

 protozoa in cultures made from soil, and suggests that the presence of these 

 animal organisms has some vital connection with the properties of the soil. 



Hartmann and Nagler,}! and Nagler,§§ have published important con- 

 tributions to our knowledge of the life-history and nuclear changes of several 

 small amoebae, three or four of which came from cultures made with soil. 



"Wolff IHI speaks of a characteristic protozoan fauna in certain irrigated 

 soils. He attributes various functions to the protozoa, viz. : — (1) Carrying 

 disease germs ; (2) taking up and killing algae, fungi, and bacteria ; 

 (3) absorption of useful material from the soil water, thus preventing it 

 from sinking to the deeper layers of soil ; and (4) power of living at all 

 seasons of the year, so long as the ground is sufficiently moist and is not 

 frozen. He gives a plate with drawings of protozoa. 



* Loc. cit., p. 142, § 42. 



t Greeffi, R, 'Arch, fur Mikroskop. Anat.,' 1866, vol. 2, p. 299. 

 X Beijerinck, ' Centr. fur Bakt.,' 1896, vol. 19, Pt. 1, p. 257. 

 § Celli, ibid., p. 1025. 



|| Frosch, P., ' Cent, fur Bakt.,' 1897, vol. 21, Pt. 1, p. 579. 

 IT Tsujitani, J., 'Cent, fur Bakt.,' 1898, vol. 24, Pt. 1, p. 666. 



** Stormer, K., ' Jahrsber. d. Vereinigung f. angewandte Botanik,' 1907, No. 5, p. 113. 

 tt Hiltner, L., ibid., p. 200. 



XX Hartmann, M., Nagler, K., ' Sitz. Ber. d. Naturf. Freunde,' 1908, Berlin, vol. 4. 

 §§ Nagler, K., ' Arch, fur Protistenk.,' 1909, vol. 15, p. 1. 



IHI Wolff, ' Mitt. a. d. Kaiser Wilhelm-Instit. f. Landw. Bromberg,' 1909, vol. 1, Heft 4, 

 p. 382 ; Abst., ' Cent. f. Bakt.,' 1909, vol. 24, p. 465. (Only abstract seen.) 



