BACTERIA IN FOODS 231 



the multiplication of many forms of water bacteria, exerts a 

 directly and highly prejudicial effect on the typhoid bacilli, 

 causing their rapid disappearance from the water, whether 

 water bacteria are present or not." It was at this time, 

 when the matter was admittedly in an unsatisfactory stage, 

 that Dr. Cartwright Wood made his experiments. 1 We 

 have not space here to enter into this work. But his con- 

 clusions seem to have been amply established, and were to 

 the effect that typhoid and cholera bacilli could, as a matter 

 of fact, exist over very lengthened periods in ordinary sea- 

 water. The next step was to demonstrate the length of 

 time the bacilli of cholera remained alive in the pallial cavity 

 and body of the oyster. Dr. Wood found they did so for 

 eighteen days after infection, though in greatly diminished 

 numbers. This diminution was due to one or all of three 

 reasons : (a) the effect of the sea-water already referred to as 

 finally prejudicial to bacilli of typhoid; (b) the vital action 

 of the body-cells of the oyster; (c) the washing away of 

 bacilli by the water circulating through the pallial cavity. 



It will have been noticed that up to the present we have 

 learned that typhoid bacilli can and do live in sea-water, 

 and also inside oysters up to eighteen days, but in ever- 

 diminishing quantities. The question now arises: What is 

 the influence of the oyster upon the contained bacilli ? 

 Under certain conditions of temperature organisms may 

 multiply with great rapidity inside the shell of the oyster. 

 Yet, on the other hand, the amoeboid cells of the oyster, 

 the acid secretion of its digestive glands, or the water circu- 

 lating through its pallial cavity, may act inimically on the 

 germs. Proof can be produced in favour of the third and 

 last-named mode by which an oyster can cleanse itself of 

 germs. So far, then, we have met with no facts which 

 make it impossible for oysters to contain for a lengthened 

 period the specific bacteria of disease. Let us now turn to 



1 British Medical Journal, 1896, ii., p. 760 et seq. 



