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XI. —ON THE CONNECTION BETWEEN OYSTERS AND 



INFECTION. 



From the earliest times more or less well grounded suspicion has been cast from 

 time to time upon shellfish — chiefly Oysters and Mussels — as being the cause of out- 

 breaks of disease amongst consumers, such as : — ist. Cases of sudden poisoning due to 

 the presence of putrefactive products in the shellfish ; and 2nd. Diseases due to a specific 

 micro-organism, where there is a period of incubation, and where therefore a consider- 

 able interval has elapsed between the infection and the actual illness. In the latter case 

 it is obviously much more difficult to determine with certainty the source from which the 

 disease germ has entered the body ; and although many positive assertions have appeared 

 of late years attributing outbreaks of enteric or typhoid fever to the consumption of 

 oysters, still it must be pointed out that the connection between the two, although quite 

 likely, has not yet been scientifically proved, and is only at present more or less of 

 a possibility, or, at most, probability. 



During the past three years we have been making a number of observations and 

 experiments, both in our Liverpool laboratories and at the Port Erin Biological Station, 

 upon the conditions under which oysters live healthily, and upon the possibility, or even in 

 some cases the probability, of their being the carriers of disease germs. During that period 

 much public interest and apprehension has been raised by several recent outbreaks of 

 typhoid popularly attributed to oysters, such as that of the Stirling Ball in October, 1895 ; 

 that of the Wesleyan University in Connecticut, investigated by Professor H. W. Conn in 

 1894; and that in the south of France attributed to Cette oysters, reported upon by 

 Dr. Chantemesse in 1896. It was obvious from these, and from numerous other outbreaks 

 of typhoid attributed to eating oysters, that the conditions under which the shellfish were 

 liable to become contaminated with sewage, and so be the carriers of pathogenic 

 organisms, required investigation. The following is a brief account of our experiments 

 and observations. 



A. The objects we had in view in entering on the investigation were as follows : — 



1. To determine the conditions of life and health and growth of the oyster by 

 keeping samples in sea-waters of different composition ; e.£:, it is a matter of discussion 

 amongst practical ostreiculturists as to what specific gravity or salinity of water, and what 

 amount of lime, are best for the due proportionate growth of both shell and body. 



2. To determine the effect of feeding oysters on various substances — both natural 

 food, such as diatoms, and artificial food, such as oatmeal. Here, again, there is a want of 

 agreement at present as to the benefit or otherwise of feeding oysters in captivity. 



