44 



dozen oysters at least eight changes, or a change of nearly 

 three litres of fresh sea water for eight or ten consecutive days 

 surely more than enough for the purpose. All that is there- 

 fore required is a small primary outlay, insignificant as com- 

 pared with the price charged for oysters to the consumer. 



Our experiments have further shown that even when 

 oysters are infected with large numbers of B. typhosus, 

 incomparably larger than would be the case under ordinary 

 natural conditions, they clean themselves in a comparatively 

 short time if kept in clean sea water ; under laboratory 

 conditions even the at first polluted oysters, having been 

 infected each with between 95,000 and 800,000 B. typhosus, 

 had done so in less than twelve days. 



Although, as pointed out on a former page, the typical 

 (fluid) typhoid stool during the third week and the typhoid 

 urine during convalescence contain enormous numbers of 

 B. typhosus amounting to many millions per each cubic 

 centimetre sewage as it flows out of the sewers, and as even 

 in the worst places it might directly bathe oyster layings or 

 oyster ponds, would in no case contain such great numbers 

 of B. typhosus as were used in our experiments. It will be 

 remembered that ordinary domestic sewage contains human 

 dejecta in a highly-diluted state, and therefore unless typhoid 

 stool or typhoid urine as such are directly allowed to bathe 

 the oysters, the number of typhoid bacilli in the sewer outfalls 

 would be under the worst conditions comparatively small. 

 So much more advantageous that the remedy against the con- 

 sumption of typhoid-infected oysters, being simple, would be 

 capable of readier application. The remedy would be this : 

 Place the oysters after removal from the polluted layings 

 in tanks or ponds receiving no other than clean sea 

 water. As far as I can see, to obtain the necessary amount 

 of clean sea water from outside the range of the polluted area, 

 and to have this frequently changed in the tanks or ponds, 

 is a simple matter of arrangement, which after a first outlay 

 would not involve more than a trifling expenditure, ludicrously 

 small if compared with the large interests at stake, the high 

 prices paid for good and safe oysters, and the big profits that 



