CULTIVATION OF OYSTERS BY NATURAL AND ARTIFICIAL METHODS. 15 



not in the summer. The greenness docs not extend throughout the whole of 

 their body, but simply to their beard or fin. The cause is totally unknown : 

 some attribute it to the green weed among which the oysters are placed ; others 

 to the infusoria upon which they feed : for all practical purposes suffice it to 

 say, they are most excellent and nutritious food to the human frame. Dr. 

 "Letheby has made an analysis of them for Mr. Wiseman, and reports that they 

 are perfectly wholesome and contain no copper. Practical experience, more- 

 over, proves that they are wholesome, and many dozens of them may be eaten 

 with impunity. The 03-sters at Marcnnes, in France, are so highly esteemed 

 by the French people on account of their greenness, that the oyster-culturists 

 at Marennes placed them in pits in order that they might become green. 

 From all that I can observe or ascertain, my present opinion is (and is fur- 

 ther confirmed by experiments which I have carried out), that the cause of 

 the greenness is the presence of chlorophyll in the beard of the oyster. 

 From this fact we may deduce an important practical conclusion, viz. that, if 

 it be desirable to get off the greenness from the oysters, all that is required 

 will be to place them in pits, and place a covering of hurdles, brands, or 

 other materials over them, so as to prevent the action of light, the chloro- 

 phyll will, I believe, not be formed, and the oyster in consequence not be able 

 to take it up. This is a practical suggestion which I have made to Mr. Wise- 

 man, and which he has promised at once to experiment on. 



Falmouth Green Oysters. 



The green oysters from Falmouth have undoubtedly a bad reputation, on 

 account of their being said to contain copper. Mr. Fox, of Falmouth, has 

 been good enough to send me samples of these oysters. I have submitted 

 them to the analysis of Mr. Tarner, who reports the presence of copper in 

 them, but in very minute quantities, hardly sufficient, I should imagine, to 

 do injury to the human system ; still that it is present there can be no doubt. 

 It may be that the oysters obtain the copper from a solution in sea-water, 

 or from the fresh water running from the copper-mines. I propose, if oppor- 

 tunity serves, to visit Falmouth, and inquire more minutely into this fact. 

 Falmouth oysters are imported in considerable quantities to the mouth of the 

 Thames ; and practical experience shows that they lose all their green colour 

 on being exposed for a few months in water suited to their fattening. The 

 bodies of these Falmouth oysters when first caught are almost as green as 

 arsenical paper ; the shells also look green in external appearance. Upon 

 placing them in spirits of wine the spirits become dark green ; there can be 

 no doubt whatever that this is caused by the presence of chlorophyll. 



In conclusion, I would remark that so anxious am I about the cultivation 

 of the waters, especially with reference to the Salmon and the Oyster, that I 

 have established, at my own expense, at the Royal Horticultural Gardens, 

 under the Science and Art Department of the South Kensington Mriseum, a 

 " Museum of Economic Fish-culture," in which I have exhibited drawings 

 and preparations illustrating the habits and natural history of the salmon, 

 together with samples of oysters from many parts of the United Kingdom. 

 The development of the young oyster from its embryonic state to the time 

 that it is fit for market, together with the various modes of its cultivation, 

 both by ordinary and by artificial methods, is fully illustrated. Samples of 

 oysters, alive or dead, from any part of the world will be most thankfully 

 received ; for any fact, however insignificant it may seem to be, is valuable. 



