2920 Notices of New Books. 



occurred, with great uniformity of symptoms, but varying very much 

 in severity, but none, so far as I know, have left any permanent bad 

 effects.' To what cause these deleterious effects are to be ascribed 

 is uncertain, for mussels, you are aware, commonly may be eaten 

 with impunity. The common people attribute all the symptoms to 

 the person having unwarily swallowed the beard or byssus of the fish, 

 but there is no doubt that the opinion is erroneous. Some of the learn- 

 ed ascribe them to the presence of parasitical worms, to the spawn 

 of starfish, or to microscopical medusas ; others to the mussel having 

 fed on some poisonous articles, more particularly on the ores of cop- 

 per ; others believe the mussels to be in a diseased condition, or in a 

 state of putrefaction ; and others refer all to the peculiar idiosyncrasies 

 of the sufferers. In many cases this latter explanation will suffice, 

 but sometimes, as in the Leith cases, it is obviously insufficient. Drs. 

 Combe and Christison have reviewed with candour the other sup- 

 posed causes, and finding reason to refuse assent to any which has 

 been alleged, they agree that the effects seem to be best explained by 

 attributing them to a peculiar poison generated in the fish under un- 

 known circumstances, although the latter eminent physician and che- 

 mist admits, that in the deleterious mussels he could not detect any 

 principle which did not equally exist in the wholesome ones. It is 

 quite certain that putridity can have no existence as a cause, for the 

 fish are eaten fresh or alive, and the most delicate chemical tests give 

 no indication of the presence of copper, which, moreover, produces 

 symptoms of a different character. Delle Chiaie has demonstrated 

 that in many instances the poison is generated with those changes in 

 the system that result from the pregnancy of the Mollusks. The 

 Area Noas, Murex brandaris, and M. trunculus, are great favourites of 

 the Neapolitans, who eat them with perfect safety in all seasons ex- 

 cept in summer or the beginning of autumn, when they are dangerous. 

 This author has recorded two examples of their fatal effects at this 

 season ; and another of a party of twelve persons who were poisoned 

 with the Area Noae, although the only one of the party who died was 

 the wife of the host. On dissection, he found that all those Mollusca, 

 at this season of fecundity, were greatly altered, more especially the 

 gland which secretes the purple fluid; and the ovaries and the 

 branchiae, and indeed the whole body, were filled with a clammy 

 liquid. I am inclined to believe, with Dr. Thomas, that in other cases 

 the poisonous principle proceeds from some particular food which, 

 not fatal to the Mollusks, yet generates a diseased condition of the 

 body deadly to other creatures. The Leith mussels were living in a 



