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ELEVENTH ANNUAL MEETING. 13 
occurring than in some much more highly-organized animals. 
It is a fact, however, that the oyster is singularly tree from 
true paragites of all kinds; the oyster crab being perhaps the 
only eh, which is ever frequently found within its valves, 
and then only as a harmless messmate. More recently it has 
been my good fortune to be able to study a second lot of Eu- 
ropean oysters, in two varieties of which the green color was 
unusually developed, especially in the heart. Ina specimen of 
Falmouth oyster I found a large cyst or sack inthe mantle near 
the edge, filled with green cells, which, like those in the heart, 
when opened readily separated from one another, being quite 
as independent of each other as the ordinary discoidal corpus- 
cles in the serum of red blood. The hearts of affected speci- 
mens were found to have the wall of the ventricle abnormally 
thick, and covered inside with the readily detachable green cells 
in athick layer and measuring 1-20o0oth of an inch in diameter. 
An application of the crucial test for starch with iodine gave a 
negative result. When iodine was first applied to these cells.in 
strong solution, and then treated with sulphuric acid, with the 
result that the characteristic blue reaction was not developed, 
showed that there was no cellulose wall covering them, and 
that they were most positively not parasitic, algous, vegetable 
organisms. In potassic hydrate solution they underwent com- 
plete solution, a further proof of the absence of cellulose. 
Their dimensions, 1-20coth of an inch, is the same as that of 
the blood-cell of the oyster. They are nucleated, with the nu- 
cleus in an eccentric position as in the blood-cell of the animal. 
Their occurrence in the heart and gills so as to tinge those or- 
gans of their owncolor is almost positive proof of their true 
origin and character. Furthermore, I find in sections that they 
sometimes occlude the blood-channel. In the cyst in the man- 
tles, as in the heart, they are free, and in the normal untinged 
heart, they are not abundant. All of the foregoing facts indicate 
that these green bodies are in reality blood-cells which belong 
to the animal. How they become green is not easy to deter- 
mine. The fact remains that no evidence of the presencc of 
green Muicrococct, or Microdia, as independent existences could 
be made out. The fact that 1 found instances in green oysters 
