These were examined by Doctor Derbes, Professor of Sciences, and Captain Solier, of Marseilles, and the result of their researches was published in the supplement of the _Comtes Rendus_ of the Académie des Sciences, in answer to a prize essay proposed by the Academy in 1847. Nothing can exceed the botanical truthfulness of the memoir presented by these gentlemen to the Academy. After a careful examination of the substances resulting from the mass of decayed sea-weed in the delta of the various rivers which flow into the Mediterranean Sea, they arrived at the conclusion that the product is the cause of fevers, by generating a malaria which the vital powers are unequal to meet. Thus the cholera existed at Marseilles in 1850; all knowledge of the extent of its destructive ravages was withheld from the public; and the truth of this is in some measure proved by the readiness with which the Board of Health recommend the quarantine of ten to fifteen days, when it was reported that the plague or cholera existed at Tripoli, Sicily, and Sardinia.--July, 1858. NOTE 6.--_The Marseilles Board of Health and Quarantine._ TO THE EDITOR OF THE “TIMES.” _Challice._ Sir,--The Board of Health of Marseilles are about to establish quarantine regulations of ten days’ and fifteen days’ duration at that port, because “a dreadful plague rages at Bengazzi, in Tripoli, and is extending along the coast to Alexandria.” Individuals are to be confined ten days, and in certain cases fifteen days. Letters are to be purified, &c., and some 1500 Piedmontese labourers are likely to be disturbed and thrown out of work if the proposed quarantine regulations are established. And so this is the sum total of sanitary experience for the last ten years! The French authorities saw all quarantine regulations broken down during the Crimean war; in fact, joined the British in abolishing a quarantine at Smyrna, at Galipoli, at Constantinople, at Sinope, at Samsoon, at Trebizonde, at Malta, and even at Marseilles, and indeed at all other ports and places used by the transports and by the armies in alliance.