At Panama, in January, 1907, my wife and I stayed in the Commission's screened hotel on Ancon Hill, not caring to face the dirt and squalor of the old city. In April, 1908, finding the city properly paved, drained, and plumbed, we took up our quarters at the Hotel Central in the town, where we spent a fortnight in perfect health; and although this building, not being under the Commission, is unscreened, I was only bitten by mosquitoes, to my knowledge, twice during that time, and this without subsequent ill effect. I may add that the picturesque surroundings, not unlike those of some city on the Mediterranean, greatly enhance the pleasure of a stay on the Isthmus, now that they can be enjoyed without squalid accompaniments. I did not, except on one or two nights, even draw the mosquito curtains. Out of doors, in the city of Panama, I was not bitten once, though I was attacked once or twice by solitary mosquitoes when walking on roads or paths with shrub or jungle adjoining. This was near the end of the dry season. When the rains commence a greater number of mosquitoes must be expected. Natives of the Isthmus and the West Indies are not immune from malaria, and in 1904-5 about one-half of the inhabitants who were examined proved to have the parasite of malaria in their blood. As the _anopheles_ becomes infectious through biting a malarious man, it is evident that such a dissemination of the parasite throughout the blood of the human population renders mosquitoes especially dangerous. In the same proportion as the population becomes less malarious, so the mosquitoes become less dangerous, and theoretically a millennium is possible in which man and _anopheles_, mutually purged of the malarial organism, may live happily together. Unfortunately, a malarious man it is believed remains infectious to _anopheles_ for no less than three years, instead of the three days' limit of yellow fever, and this greatly increases the difficulty of exterminating malaria. During 1906, with a force of 26,000, there were 21,739 cases of malaria admitted to the Commission Hospitals, and the death-rate from this disease was among whites 2 per thousand, among negroes 8 per thousand. In 1907, with a force of 39,000, there were 16,753 cases, the death-rate among whites being 3 per thousand and among negroes 4 per thousand. The increase among whites was due to the greater proportion of the European labourers, whose circumstances are different from those of the skilled artisans and the "screened" clerical staff of Americans. The total death-rate from all causes in 1907 is shown below:--