Take the first case forming what is represented as the first link in this presumed chain, the seizure with fever of the two guards at the Fort. Two European soldiers lately arrived in the colony, and therefore peculiarly predisposed to an attack of endemic fever, go from Boa Vista, which at that time was healthy, to a confined, unventilated, overcrowded, and filthy spot on another island, where fever was raging to such a degree that within the space of three weeks there had occurred no less than 60 attacks and 33 deaths, in a crew consisting on the arrival of the ship of 117 officers and men. There is in this no evidence of the propagation of disease by a specific contagion; on the contrary, it is the ordinary production of disease by its ordinary cause, namely, exposure to a polluted atmosphere, the pollution being, in this instance, excessive from overcrowding; from accumulation of filth; from foul and offensive privies; from the impossibility of the admission of fresh air, owing to the construction of the building, and from the intense and oppressive heat, the thermometer ranging from 81° to 86° of Fahrenheit. The seizure of two men with fever under such circumstances is precisely analogous to the attack of persons, previously healthy, with typhus, who take up their abode in the crowded and filthy courts and alleys of English towns. Take the next link in the chain, the attack of the negro soldier. The circumstances respecting this man, being precisely the same as those relating to the two other guards, the same answer would have sufficed for both, but according to the testimony of the man himself, his illness was very slight, and his companion who was sent to lodge with him at the hut in Porto Sal Rey, had no illness at all during the whole time of their seclusion. The third link in the chain is the presumed fact, that a woman (Anna Gallinha), who lived next door to the hut in which these two men had been confined, was seized with fever soon after they had left it, and that she was the first person attacked, at least whose illness attracted public attention, in the town of Porto Sal Rey. Dr King states, that on a personal examination of the soldier who had experienced the slight attack of fever, he said that during the seventeen days that he and his companion were confined to the hut, “they had no communication with any one.” Dr M‘William, on the other hand, affirms that Gallinha was a frequent visitor at the hut, and, indeed, cooked for the men. Supposing Dr M‘William’s account to be the correct one, it is surely more reasonable to attribute the attack of Gallinha to the local causes to which she was exposed, and which Dr M‘William admits were sufficient to account for her illness, than to contagion derived from a man whose illness was so slight that it had not confined him to his bed for a single day, and which was incapable of infecting his companion who was constantly with him night and day.