162 TRANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



to determine the number of micro-organisms present, as 

 well as the identity of the typhoid or other pathogenic 

 organisms. 



C. The following is a summary of the results obtained 

 so far : — 



"We consider that these results are based upon tentative 

 experiments, and serve only to indicate further and more 

 definite lines of research. They must not be regarded as 

 conclusive. We feel strongly that all the experiments 

 must be repeated and extended in several directions. 



Our experiments demonstrate : — 



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 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. 



III. The deleterious effects of stagnation, owing to 

 the collection of excretory products, growth of micro- 

 organisms, and formation of scums upon the surface of 

 the water. 



IV. The toleration of sewage, etc. 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 



