22 POISONOUS MOLLUSCA. 



cious quality to the oyster, probably by acting as the cause 

 of some disease. The fact was communicated to Dr. Chis- 

 holm, " at St. Croix, by the late Mr. William Newton, of that 

 island. Some time after the Santa Monica, British frigate, 

 was cast away on the coast of the island of St. Jolm, one of 

 the Virgin Islands, oysters grew on her bottom, which was 

 coppered. Many people ate of these oysters, and although 

 the consequence was in no instance fatal, it was such as was 

 dangerous and unpleasant in a very great degree, producing 

 cholera and excruciating tormina."* Further observations 

 and experiments are, however, necessary to elucidate this 

 interesting question. Lamouroux states that mussels never 

 become poisonous unless they are exposed alternately to the 

 air and the sea in their place of attachment, and unless the 

 sea flows in gently over them without any surf ; but on this 

 statement it may be remarked that mussels are almost always 

 found in such localities, where they certainly thrive best. 



* Edin. Med. Surer. Journ. iv. 400. 



