&2 The JVon-persisfence of Bacferio-toxius in f/ic Soil 



to heat. Concomitautly, acid iron and alumina compounds which are 

 removed from the soil by the action of the saline solution are thrown out 

 of action. The "toxicity" of this soil can be rapidly (within 24 hours) 

 and effectively removed by treatment with calcium carbonate. 



8. Alternate inoculation and removal of the bacterial growth by 

 filtration rapidly yields an extract unfavourable for the growth of 

 B. prodlgiosus: this is in part due to the impoverishment of the extract 

 in food material, and also to the formation of some substance inimical 

 to growth. This body is capable of passage through a porcelain filter 

 and is heat .stable: it therefore appears to have little in common with 

 the inhibitory bodies described by Rahu as occurring in cultures of 

 organisms such as B. fluorescens liquefaciens or B. coli, nor does it re- 

 semble, in its relations to heat, the toxins which are alleged to occur in 

 the soil. 



9. Although it is possible, under well-defined conditions, to induce 

 the formation of bacterio-to.xins in culture solutions, there is no evidence 

 to show that these are likely to possess importance in the phenomena of 

 partial sterilisation of soil. 



REFERENCES. 



1. R0.SSELL, E. .J. and Hutchinson, H. B. This Jounuil, 1909, 3, 111—144; 1913, 

 5, 152-221. 



2. Greio Smith, R. Proc. Linn. Soc. A..S. II'. 1910, 25, 808-822; 1911, 26, 679-699. 

 Cent. BaLi. Par. ii, 191 1, 30, 154-156. 



3. BoTTOMLEY, VV. B. Pep. Hril. Ad. Sci. 1911, 60S. 



4. Hutchinson, C. M. Mem. hid. Dep. Agr. 1912, 1, pt. 1 (Bact. Ser.). 



5. DAIKUH.4RA. Bui. Jap. Int. Cent. Agric. Exp. Stal. 1914, 2, 1-40. 



6. Rahn, O. Cent. Bakt. Par. ii, 1906, 16, 417. 



{Received January 17tk, 1918.) 



