ON THE CONNECTION BETWEEN OYSTERS AND INFECTION. 37 



{d) A series of oysters weighed approximately, and fed upon the 

 following substances, viz: — (i) Oatmeal, (2) Flour, (3) Sugar, (4) Broth, 

 (5) Living Protophyta (Diatoms, Desmids, Algae), (6) Living Protozoa 

 (Infusoria, &c.), (7) Earth. 

 In this series of experiments the oysters were fed every morning, and the water 

 was aerated but not changed (evaporation was compensated for by the addition of a 

 little tap water as required). The oysters were weighed from time to time, and obser- 

 vations made upon the apparently harmful or beneficial effects of the above methods of 

 treatment. 



{e) A series of oysters placed in sea-water to which was added daily : — 

 (i) Healthy faecal matter. 



(2) Typhoid faecal matter. 



(3) Pure cultivations of the typhoid bacillus. 



The oysters were carefully examined to determine their condition, with special 

 reference to condition of branchiae, alimentary canal, adductor muscle, liver, and viscera 

 generally. 



The contents of the rectum, as well as the water in the pallial cavity, were subjected 

 to bacteriological analysis, to determine the number of micro-organisms present, per 

 cubic cm., as well as the identity of the typhoid or other pathogenic organisms. 



C. The following is a summary of the results obtained : — 



I. The beneficial effects of aeration : — 



{a) By the addition of air only, 



{b) By change of water : 

 pointing to the conclusion that the laying down of oysters in localities where there is a 

 good change of water, by tidal current or otherwise, should be beneficial. 



II. The diverse results obtained by feeding upon various substances, amongst 

 which the following may be noted : — The exceedingly harmful action of sugar, which 

 caused the oysters to decrease in weight and then die ; whilst the other substances 

 detailed above enabled them to maintain their weight or increase. The oysters thrive 

 best upon the living protophyta and protozoa. Those fed upon oatmeal and flour 

 after a time sickened, and eventually died. Some were fed upon quantities of a minute 

 green alga (Microcystis), which we happen to have in abundance in a fountain. This 

 did not result in any greening of any part of the oyster. 



III. The deleterious effect of stagnation, owing to the collection of excretory 

 products, growth of micro-organisms, and formation of scum upon the surface of the 

 water. 



IV. The toleration of sewage, &c. It was found that oysters could, up to a 

 certain point, render sewage-contaminated water clear, and that they could live for a 

 prolonged period in water rendered completely opaque by the addition of fsecal matter ; 

 that the faecal matter obtained from cases of typhoid was more inimical than that 



