228 BIOLOGICAL PROBLEMS 



two soils, with a certain amount of doubt, and it is 

 at any rate not very abundant in the soil. Nor is it 

 found in the intestines in more than i to 2 per cent of 

 persons. Very likely the soil is its permanent reposi- 

 tory, but it only gets a chance to luxuriate where 

 wounds and dead animal tissue abound. Hence cer- 

 tain places will get saturated with it at certain times, 

 and in such a place, by great good luck we found it. 



R. C. M. 



