SEA-FISHERIES LABORATORY. 345 



obtained by adding either copper coins, copper foil, or 

 salts of copper to water; when copper foil is used 

 sufficient copper is dissolved by the distilled water in 

 one to five minutes to kill the typhoid organisms within 

 two hours. 



" 7. A solution of copper may lose its toxicity by 

 the precipitation of the copper as an insoluble salt or 

 compound, by its absorption by organic substances, or 

 by absorption by insoluble substances. 



kk 8. The oligodynamic action of the copper is 

 dependent upon temperature, as first pointed out by 

 Israel and Klingmann. 



"9. The effects of oligodynamic copper in the 

 purification of drinking water are in a quantitative 

 sense much like those of filtration, only the organisms 

 removed, like B. typhi and B, coli, are completely 

 destroyed." 



Now if these results can be extended to the case 

 of marine shell-fish, it may be argued that if 

 the typhoid organism is killed in two hours by 

 distilled water in which copper foil has been placed for 

 five minutes, a comparatively simple measure of washing 

 ought to be sufficient to render contaminated oysters 

 innocuous. The importance of such a result is obvious. 

 It may be asked why, considering the rather large amount 

 of copper that may be present in the tissues of the oyster, 

 should the copper foil be necessary. It is known, how- 

 ever, to be the case that in the normal oyster the copper 

 of the blood is united with a proteid to form an organic 

 compound, haemocyanin, in such a way as to be unable to 

 exercise its toxic properties. It is probable that that is also 

 the case in these abnormal green oysters which Professor 

 Boyce and I investigated* some years ago, and where we 



■>'- On a green Leucocytosis in Oysteib. Proc. Royal Society, vol. 

 lxii., p. 30 (1897). 



