On a Green Leucocytosis in Oysters. 



37 



treatment with ammonium sulphide before any dark coloration is ob- 

 tained with that reagent. Now it will be observed that all onr reactions 

 were immediate, taking place directly on the addition of ammonium 

 sulphide, or potassic ferrocyanide alone, or aided by a trace of acid. 

 The copper was therefore present in a condition analogous to the 

 inorganic iron, or at least so loosely combined with the cell proto- 

 plasm as to be readily discharged, but in none of these cases did we 

 get any indication of inorganic iron, except in the case of the 

 contents of the alimentary tract of the oyster. When the sections 

 were treated with 3 per cent, nitric acid in alcohol for half an honr 

 the green colour disappeared, and then neither the copper reaction 

 nor the striking reactions with ammonium sulphide and haematoxylin 

 took place. Snbsequent treatment of these sections with acidulated 

 potassic ferrocyanide, and again washing in dilute nitric or hydro- 

 chloric acid, yielded a general and very faint Prussian blue reaction, 

 in which the nuclei of the gland cells were more markedly blue than 

 the leucocytes. If the method is reliable it shows that traces of iron 

 are present in the cells in addition to the copper, but it is the organic 

 iron. Some oysters gave this Prussian blue reaction more markedly 

 than others; this was the case with some Falmouth li natives." 



Heemocyanin containing copper has been shown to be an 

 important constituent of the blood in many of the invertebrata, 

 taking the place of haemoglobin. We have examined the blood of 

 very many oysters, and only in two instances, and these in green 

 oysters, have we thought that the plasma became very faintly blue 

 on exposure to oxygen, whilst, as previously indicated, qualitative tests 

 either failed to give any indication of copper or, at most, only a very 

 faint reaction, and even in these cases the reaction appeared confined 

 to the leucocytes which were present in the plasma. The ash, how- 

 ever, of the white oyster yields about 0'006 grain of copper, and it 

 is probable that minute traces are present in the plasma as heemo- 

 cyanin. The cause, then, of the presence of the copper in such 

 abundance in the green leucocytes is very obscure. The quantity of 

 copper in the green leucocytes themselves varies, as our histo- 

 chemical reactions demonstrated ; some corpuscles could be found 

 which were conspicuous by their red reactions on the addition or' 

 potassic ferrocyanide, whilst others in the same preparations only 

 gave very faint indications, and occasionally a cell could be seen 

 which gave a marked Prussian blue reaction instead of the red. 



Conclusions. 



Our results demonstrated the presence of copper in comparatively 

 large quantity in the green leucocytes, chiefly in the American 

 oyster, but also in the " natives " from Falmouth and other localities. 



