7° FISH—CULTURAL ASSOCIATION. 
probable that Prof. Leidy was one of the first to notice the in- 
tercellular parasitism of a plant in an animal. 
The green color of the oyster, as far as my experience goes, 
is not intense, as in many green animals, such as we observe in 
Stentor, Spongilla, Hydra, etc., but is a pale pea-green tint. This 
has been found to be the color of affected natives as well as of 
foreign ones, the gills and mantle being usually most distinctly 
tinged. Exceptionally the heart is affected, its color sometimes 
being quite intense. 
In studying some oysters which were obtained from England 
through the kind offices of Messrs. Shaffer and Blackford, in 
response to a request coming from Prof. Baird, certain ones 
were found which were decidedly green. Of these the French 
specimens of Ostrea edulis, and a very singular form, labeled 
‘““Anglo-Portuguese,” had the gills affected, and in some of the 
latter the liver, heart and mantle were very deeply tinged in cer- 
tain parts, so much so that I decided to make as critical an ex- 
amination as my resources could command. 
Spectroscopic investigations gave only negative results, as it 
was found impossible to discern any positive evidence of chlor- 
ophyll from the spectrum of light passed through thin prepara- 
tions made from specimens of green-tinted oyster, some of which, 
like those from the heart, are decidedly green to the naked eye. 
There was no absorption noticed at the red and blue ends of the 
spectrum, such as is observed when the light which enters the 
slit of the spectroscope first passes through an alcoholic solution 
of leaf-green or chlorophyll; indeed, the spectrum did not appear 
to be sensibly affected by the green substances which causes the 
coloration of the oyster. No attempt was made to test the mat- 
ter with the use of alcoholic green solutions obtained from 
affected oysters, as the former are not easy to get with a suffi- 
cient depth of color, because of the relatively small amount of 
coloring matter present in the animals. Unstained prepara- 
tions were used in all of these experiments. 
Finally, in order to see if the color was due to the presence of 
some green compound of copper, Professor H. C, Lewis, of the 
Academy of Natural Sciences of Philadelphia, kindly made 
some delicate tests tor me, using small, dried fragments of an 
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