86 Papers from the Department of Marine Biology. 



it. After their return from the banks, the poison gradually leaves 

 them and they become wholesome again. 



Chisholm notes that copper is supposed to be the essential basis of 

 this poison, but adds that he knows of "no facts which decidedly 

 prove this." As to the value of salt as a preventive he says: 



"A barracuda, the poisonous quality of which was proved by its entrails 

 killing a cat which had ate of them, being cut into slices or junks, and slightly 

 salted or corned, was rendered perfectly wholesome, and, as usual delicious 

 to the taste. Instances have occurred, however, in which salt has not 

 exhibited its counteracting power." 



Moreau de Jonnes, as early as 1819, and 1821, made extensive and 

 intensive studies of poisoning resulting from eating fishes, the barracuda 

 among others. In his later and fuller paper, he quotes various authors 

 that crabs which eat the fruit of the manchineel become poisonous 

 (thus confirming that very accurate observer, William Dampier), while 

 those which have no access to this fruit are wholesome. He then 

 takes up and disposes of the alleged causes of the poisonous quality of 

 the flesh of certain fishes. He states that the first cause commonly 

 assigned is that the fishes eat poisonous zoophytes. This he rejects 

 because poisonous fish are found where these are absent and whole- 

 some fish where they abound, because the same fish where these abound 

 are not poisonous throughout the year, and lastly because he fed poi- 

 sonous hydroids of all kinds to fishes and then fed these fishes to vari- 

 ous animals and to man with impunity. The second reason adduced is 

 that the fishes are poisoned by copper. Moreau de Jonnes, however, 

 notes that copper is present and fishes wholesome on the English coast 

 and that copper is absent and fishes poisonous in the West Indies, and 

 finally that oysters grow on the copper bottoms of vessels and have been 

 found wholesome when eaten. Then he takes up the manchineel 

 theory. He notes that no one has ever proved that fishes eat the man- 

 chineel fruit, and that he has made many dissections of poisonous 

 fishes (barracudas among them) without ever having found fragments 

 of the manchineel fruit in them. He thinks that the eaters would be 

 killed by the eating, and that, since these trees abound widely on sea- 

 shores, there should be many more poisonous fish and crabs than there 

 are. Finally, for himself he concludes that poisoning from eating 

 fishes (barracudas included) is due to the fact that the flesh has some 

 inherent poisonous properties, or develops such morbid qualities as a 

 result of the hot climate. While our author gives the former explana- 

 tion his very strong belief, we have in the second a premonition of the 

 ptomaine theory. 



Another physician, William Ferguson, writing some years later 

 (1823), declares that the size of the fish has nothing to do with its 

 poisonous qualities, nor does the use of salt destroy its noxious prop- 

 erties. Then he refers to a report from a physician in Martinique 



