3IO PATHOGENIC BACTERIA IN MILK 



poisoned. In all probability such rapid multiplication occurs in 

 the human body immediately such water or milk is consumed. 



Another point which must not be wholly passed over, has refer- 

 ence to the saprophytic faculties of the B. typhosus. Some author- 

 ities consider that this bacillus can remain alive and virulent for 

 months outside the human body. In sterilised stools it has been 

 found, for example, that the bacillus can retain vitality for months. 

 On threads soaked in cultures, they have remained alive for a year, 

 on potato for two years, in sterilised garden soil 21 days, on wood 

 30 days, on sterilised linen 60 days, and on woollen cloth for 80 

 days.^ In sterilised distilled water, they have been found alive 196 

 days after introduction. When dried in various ways they have 

 lived several months Such facts as these have been taken as 

 indication of some degree of saprophytic existence being attribut- 

 able to the B. typhosus. Moreover, this theory has gained strength 

 from experiments recently conducted for the Local Government 

 Board by Dr Sidney Martin, upon the vitality of this bacillus in 

 soils. Martin found that samples of soil polluted with organic 

 matter formed a favourable environment for living bacilli of typhoid 

 fever for so long as 404 days, whereas in sterilised soil, without 

 organic matter, these organisms lived only 23 days. When, 

 however, the bacillus is placed in unsterilised natural soil containing 

 ordinary soil bacteria, the B. typhosus ceased to exist within 24 

 hours.^ Robertson, Klein, and others, have also obtained results 

 with the bacillus in soil. But these various records must be accepted 

 with some reserve, not alone on account of the fact that Eberth's 

 bacillus has not been fully proved to be the specific bacillus of 

 typhoid fever, but because we have as yet only an elementary 

 knowledge of bacteria in the soil, and the entire question of the 

 saprophytism of pathogenic bacteria is an abstruse and obscure 

 problem. It seems difficult to believe that a non-sporulating bacillus 

 of comparatively mild resisting powers can remain dormant and 

 yet alive and virulent for long periods outside the body. But 

 increasing evidence is forthcoming to show that it may be so. 



The most recent experiments in regard to this matter were 

 made by Firth and Horrocks, and in some ways they appear to be 

 the most reliable. They have shown that the typhoid bacillus can 

 survive in ordinary earth for more than two months, whether such 

 soil be virgin or polluted with sewage, or indeed frozen hard. It 



^ See also Report to Clinical Society of London, vol. xxv., 1892. 

 2 Twenty-Eighth Annual Report of the Local Government Board, 1898-99 

 (Medical Officer's Supplement). 



