232 BACTERIA 



their opportunity for acquiring such disease germs. It is 

 afforded them during the process of what is termed " fatten- 

 ing. " By this process the body of the oyster acquires a 

 plumpness and weight which enhances its commercial value. 

 This desired condition is obtained by growing the oyster in 

 ' brackish " water, for thus it becomes filled out and me- 

 chanically distended with water. But if this water contains 

 germs of disease, what better opportunity could such germs 

 have for multiplication than within the body-cavity of an 

 oyster ? " The contamination of sea-water, therefore, in 

 the neighbourhood of oyster-beds may undoubtedly lead to 

 the molluscs becoming infected with pathogenic organisms " 

 (Wood). Yet we have seen that, apart altogether from the 

 individual susceptibilites or otherwise of the consumer, there 

 are in the series of events necessary to infection many occa- 

 sions when circumstances would practically free the oysters 

 from infection. 



The sources of pollution of oysters are not the fattening 

 beds alone. The native beds also may afford opportunity 

 for contamination. Thirdly, in packing and transit, and 

 fourthly, in storage in shops and warehouses, there is fre- 

 quently abundant facility for putrefactive bacteria to gain 

 entrance to the shells of oysters. 



Dr. Klein's researches * into this question have been 

 wholly confirmatory of the facts elicited by Dr. Cartwright 

 Wood. Despite the tendency of the bacilli of cholera and 

 typhoid to die out quickly in crude sewage, the sewage is 

 sufficiently altered or diluted at the outfall for these organ- 

 isms to exist there in a virulent state. We may give Dr. 

 Klein's conclusions: 



1. That the cholera and typhoid bacilli are difficult of 

 demonstration in sewage known to have received them. 



2. Both organisms may persist in sea-water tanks for two 



1 Special Report of the Medical Officer to the Local Government Board on 

 Oyster Culture, etc., 1896. 



