24 OYSTKRS AND DISEASE. 
Total hvii present in Oysters. 
Kind of Oyster. 
Number 
Annlyzed. 
Total Iron. 
Grme. 
Weight of 
Ash. 
Mgrme. Iron 
per Oyster. 

Percentage 
Iron on Ash. 
Huitrcs dc A'Tni'onncs 
5 
0.7860 
0.23 
Dutch 
0.0009 
0-1393 
0.15 
0.65 
American 
! 
0.0018 
0.2791 
0.36 
0.64 
Colne 
lO 
0.0020 
1.0938 
0.20 
0.18 
Deep Sea 
O.C064 
1-5017 
0.32 
0.43 
Falmouth 
6 
0.0016 
0.4534 
0.27 
0.35 
In considering the variations in quantity, the very small amounts of metal present 
must be borne in mind. 
From these figures in the above tables it is evident that there is not an 
excessive quantity of iron in the gills of the green oysters — the proportion of iron in 
the gills as compared with the rest of the body is somewhat more (1:2) than that 
found in Dutch oysters (i : 3.7), but much less than in American oysters, which are 
white (1.4 : i). The comparison is purposely made on the absolute quantity of metal 
in the gills and the rest of the body, as any other basis for calculation is fallacious. 
Chatin and Muntz reckon on the weight of the dried organic matter present, 
but it was not found possible to get anything approaching constant weights in this way. 
This may to some extent account for the difference in our results, but we should also 
like to point out that although the ratio of iron in the gills and the rest of the body in 
green and in brown oysters is from i : 1.8 (feebly green) up to i : 2.3 (very green), they 
also instance white oysters with a proportion of i : 1.6. 
It is certainly somewhat strange that they find more iron in the gills than in the 
rest of the body in all cases, which is not the case in our own experiments. But the 
quantities of metal present are so small that, since they do not state how many oysters 
were taken for analysis, and employ the permanganate method for the estimation of the 
iron, it is difficult to say what degree of absolute accuracy their results represent, and 
therefore to judge in how far their analytical data justify their conclusions. 
From two points of view the above results show that the greenness of the gills 
of French oysters is certainly not due to iron : — 
(1) Because the gills of the green oyster contain less iron than the rest of the body. 
(2) Because the proportion of iron in the gills as compared with the rest of the 
body in white (American) oysters is greater than in the green. 
That our method is reliable is .shown by two determinations of the iron in the 
gills of American oysters, one giving 2.3 and the other 1.8 mgrme. of iron per six sets 
of gills. Variations in the size of the oysters will of course account for small differences, 
especially with the bodies. 
