150 BACTERIA IN THE SOIL 



results very little different from four to five year old samples. The 

 B. coli readily dies out in such refuse heaps, from which Dr Savage 

 infers that the B. typhosus, being a less resistant organism, would still 

 more rapidly die out, and that therefore "the danger of specific 

 typhoid contamination from building on such made-soil can be 

 neglected." * 



From what has been said, it will be seen that though a consider- 

 able amount of knowledge has been obtained respecting bacteria in 

 the soil, it may be conjectured that actually there is still a great deal 

 to ascertain before the micro-biology of soil is in any measure com- 

 plete or even intelligible. The mere mention of the bacilli of tetanus 

 and typhoid in the soil, and their habits, nutriment, and products 

 therein, not to mention the work of the economic bacteria, is to open 

 up to the scientific mind a vast realm of possibility. It is scarcely too 

 much to say that a fuller knowledge of the part which soil plays in 

 the culture and propagation of bacteria may suffice to modify 

 many views in preventive medicine. True, our knowledge at the 

 moment is rather a heterogeneous collection of isolated facts and 

 theories, some of which, at all events, require ample confirmation ; 

 yet still there is a basis for the future which promises much con- 

 structive work. 



* Jour, of Sanitary Institute, 1903, vol. xxiv., pt. iii., pp. 442-458. 



