27 
leucocytosis are always more or less green, but must not be 
confounded with ordinary green-gilled Oysters, where the 
colour is due to a totally distinct cause. Later in the 
summer, at the Toronto meeting of the British Associa- 
tion, we gave a further account of our investigations up 
to date, and from that report I quote the following account 
of the micro-chemical part of the work * :— 
“The following are our details of the histo-chemical 
investigation of the pigment. The green pigment is 
insoluble in boiling alcohol, ether, chloroform, xylol, and 
other fat solvents; it is soluble in dilute acids and alkalies. 
The addition of potassic ferrocyanide to sections contain- 
ing the green colouring matter, or to the leucocytes 
themselves, gives a red reaction, indicating the presence 
of copper; but the reaction can be most readily obtained 
by the addition of a small quantity of °5 per cent. hydro- 
chloric acid to the potassic ferrocyanide. Ammonium- 
hydrogen sulphide gives also an immediate reaction with 
the green pigment. Ammonia strikes a beautiful blue 
wherever there is a green. It was then found that pure 
hematoxylin is an extremely delicate test, giving an 
immediate blue reaction in exceedingly dilute solution. 
Previous treatment of the green colouring matter by 3 per 
cent. nitric acid in alcohol prevented these reactions, and 
subsequent treatment with acidulated potassic ferrocyanide 
resulted in a very faint general prussian blue colouration 
of the tissue generally. We concluded that there was no 
inorganic tron present in the leucocytes, that the leuco- 
cytes which form the green patches contain a considerable 
quantity of copper, and that, just as in the case of iron, 
as shown by Professor Macallum, pure hematoxylin is a 
most delicate test, but that great care must be taken to 
* For further details on some points see Proceedings of Royal Society, 
vol. LXII., p. 30, 1897. 
