OYSTERS AND METHODS OF OYSTER-CULTUEE. 337 



GREENING. 



Kotwithstandinfic tliat almost every recent writer upon the subject 

 has insisted upon the harnilessness of the green coloration which is 

 frequently observed in certain portions of the oysters, there is still con- 

 siderable misapprehension of the subject by consumers and oystermen 

 alike. Tlie prejudice is confined to America, in Europe such oysters 

 being regarded as superior, and much trouble being taken to impart to 

 tbem their peculiar viriditj^ In our waters the greening is liable to 

 occur in certain localities and at irregular times. Eather shallow 

 waters appear to be more susceptible to the production of this effect 

 than the greater depths, but it has recently appeared on the deep-water 

 beds of Lo]ig Island Sound. 



When oysters become so colored the oystermen find great difficulty 

 in disposing of them, owing to the ])opular belief that they are unfit for 

 food, or even j)oisonous. They often have what is described as a cop- 

 ])ery taste, and uninformed persons usually assume that the green color 

 is due to the presence of copper. A number of careful investigations 

 have shown that such oysters contain no copper whatever, but that the 

 green color is derived from a harmless blue green substance, phyco- 

 cyanin, which is found in certain of tlie lower plants. 



Under proper conditions tliese unicellular vegetable organisms mul- 

 tiply in brackish or saline water with great rapidity and provide an 

 important item of food to the oyster. The green matter is soluble in 

 the juices of the oyster and passes into the tissues, affecting principally 

 the blood corpuscles. 



An oyster usually shows the first indication of greening in the gills 

 and pali)S, and frequently this is the only portion of the animal which is 

 colored, a fact which is explained wln-u we remember that this is the 

 most highly vascular portion. When the supply of greeniiig food is 

 abundant and long continued, the mantle, liver, and eventually the 

 entire organism, with the exception of the muscle, acquire a green 

 hue. Such oysters are usually, but not always, fat and well fed, the 

 result of the abundant supply of nutritious food, and such a condition 

 could hardly obtain were the dye a copper product, such as has been 

 popularly supposed. 



The color may be removed from the oysters by transferring them for 

 a short time to waters in Avhich the green food is deficient, a fact 

 which may be available in preparing for market oysters which popular 

 prejudice refuses to use in the green state. 



In conclusion, it may be again insisted that the greening is not a 

 disease, nor a x)arasite, nor a poisonous material in any sense. 



F. C. R. 1897 22 



