54 OYSTERS AND DISEASE. 



8. In the Falmouth oysters, containing an excessive amount of copper, we find that 

 much of the copper is certainly mechanically attached to the surface of the body, and is 

 in a form insoluble in water, probably as a basic carbonate. In addition to this, however, 

 the Falmouth oyster may contain a much larger amount of copper in its tissues than does 

 the normal colourless oyster. In these Falmouth oysters the cause of the green colour 

 may be the same as in the green American oyster. 



9. By treating sections of diseased American oysters under the microscope with 

 potassium ferrocyanide and various other reagents, we find that the copper reactions 

 correspond in distribution with the green colouration ; and we find, moreover, from these 

 micro-chemical observations that the copper is situated in the blood-cells or leucocytes, 

 which are greatly increased in number. This condition may be described as a green 

 leucocytosis, in which copper in notable amount is stored up in the leucocytes. 



10. We find that an aqueous solution of pure haematoxylin is an extremely delicate 

 test for copper, just as Macallum found it to be for iron. 



11. Experiments in feeding oysters with weak solutions of various copper and iron 

 salts gave no definite results — certainly no clear evidence of any absorption of the metals 

 accompanied by " greening." 



12. Although we did not find the Bacillus typhosus in any oysters obtained from the 

 sea or from the markets, yet in our experimental oysters inoculated with typhoid we were 

 able to recover the organism from the body of the oyster up to the tenth day. We show 

 that the typhoid bacillus does not increase in the body or in the tissues of the oyster, 

 and our figures indicate that the bacilli perish in the intestine. 



13. Our experiments showed that sea-water was inimical to the growth of the 

 typhoid bacilli. Although their presence was demonstrated in one case on the 21st day 

 after addition to the water, still there appeared to be no initial or subsequent multiplication 

 of the bacilli. 



14. In our experiments in washing infected oysters in a stream of clean sea- water 

 the results were definite and uniform : there was a great diminution or total disappearance 

 of the typhoid bacilli in from one to seven days. 



15. The colon group of bacilli is frequently found in shellfish as sold in towns, 

 and especially in the oyster ; but we have no evidence that it occurs in Mollusca living 

 in pure sea-water. The natural inference, that the presence of the colon bacillus invariably 

 indicates sewage contamination, must, however, not be considered established without 

 further investigation. 



16. The colon group may be separated into two divisions — (1) those giving the 

 typical reactions of the colon bacillus, and (2) those giving corresponding negative 

 reactions, and so approaching the typhoid type ; but in no case was an organism giving all 

 the reactions of the B. typhosus isolated. It ought to be remembered, however, that our 

 samples of oysters, although of various kinds and from different sources, were in no case, 

 so far as we are aware, derived from a bed known to be contaminated or suspected of 

 typhoid. 



