R. A. Fisher, H. G. Thornton, and W. A. Mackenzie 359 



(11) Thornton, H. G. (1922). On the development of a standardised agar medium 



for counting soil bacteria, with especial regard to the repression of spreading 

 colonies. Annals of Aj^plied Biology, ix. 



(12) Engberdinu, D. (1909). V'ergleichende Untersuehungen iiber die Eakterienzahl 



im Ackerboden in ihrer Abhangigkeit von ausseren Eintlussen. Centralblall 

 fur Bakleriologie, Abt. n. Bd. 23, p. 569. 



(13) Breed, R. S. and Stocking, W. A. (1920). The accuracy of bacterial counts 



from milk samples. New York Agr. Exp. Station. Technical Bulletin, 

 No. 75. 



(14) Owen, W. (1914). Investigation of the comparative values of various culture 



media for the quantitative determination of microorganisms in cane sugar 

 pi'oducts. Centralblatt fur Bakleriologie, Abt. ii. Bd. 42, p. 335. 



(15) Buddin, W. (1914). Partial sterilisation of soils by volatile and non- volatile 



antiseptics. Journal of Agricultural Science, vi. 417. 



(16) Wyant, Z. N. (1921). A comparison of the technic recommended by various 



authors for quantitative bacteriologicil analysis of soil. Soil Science, xi. 295. 



(17) Cutler, D. W., Crump, L. M., and Sandon, H. (1922). A quantitative investiga- 



tion of the bacterial and protozoan population of the soil, with an account 

 of the protozoan fauna. Phil. Trans. Roy. Soc. B. 



{Received July 21st, 1922.) 



