The conditions of life on the low malarious Mexican coast are at any time trying to the thick-skinned whites, and unacclimated men from the north; but, in war time, the dangers were vastly increased. The marines left at the ports when on duty had to endure the piercing rays of the sun at mid-day and the heavy dews at midnight, and to beat off the guerrillas who skirmished in darkness. Added to this, were the investigations or excavations which mosquitoes, sandflies, centipedes, scorpions and tarantulas, were continually making into the human flesh with every sort of digging, fighting, chewing, sucking, and stinging instruments with which the inscrutable wisdom of the Almighty has endowed them. Added to these foes without, was that peculiar form of _delirium tremens_ prevailing along the rivers and brought on by tropical heat with which some of the Americans were afflicted. The victims, prompted by an irresistible desire to throw themselves into the water, were often drowned. Hitherto only known in Dryden’s poetry American officers now bore witness to its violence. On the ships, the miasma arising from decaying kelp washed upon the barren reefs and decomposed by the sun’s rays created the atmospheric conditions well suited for the spread of vomito. A sour nauseating effluvia blew over the ships all night, and easily operated upon the spleen or liver of those who, from exposure, fatigue or intemperate habits, were most predisposed. The Commodore convened a board of medical officers on board the _Mississippi_ prior to her departure to inquire into the causes of the disorder. In their opinion, it was atmospheric,—a theory justified by the fact that patients convalesced as soon as the ships moved out to sea. The theory of inoculation by flies, mosquitoes and other insects was not then demonstrated as now, though for other reasons netting was a boon and protection to the hospital patients. One of the first cases, if not the very first case, of yellow fever attacking a ship’s crew in the American navy was that on board the _General Greene_, commanded by M. C. Perry’s father in 1799. Coming north from the West Indies to get rid of the disease, it broke out again at Newport. So virulent was the contagion, that even bathers in the water near the ship, were attacked by it. The memories of his childhood, which had long lain in his memory as a dream, became painfully vivid to the Commodore as he visited the yellow fever hospital, and saw so many gallant officers and brave men succumb to the scourge. “King Death sat in his yellow robe.” Soon even the robust form of the Commodore succumbed to the severe labors exposure and responsibilities laid upon him, though fortunately he escaped the yellow fever. Four officers died in one week; but Perry, after a season of sickness, recovered, and, on the approach of autumn was up again and active.