Of the six important tropical diseases, plague, which reached the Isthmus one year, was quickly held in check. Yellow fever, the most dreaded of them all, never recurred. Beri-beri, which in 1906 caused sixty-eight deaths, has gradually disappeared. The hookworm disease, ankylostomiasis, has steadily decreased. From the very outset, malaria has been taken as the measure of sanitary efficiency. Throughout the French occupation it was the chief enemy to be considered, not only because of its fatality, but on account of the prolonged incapacity following infection. In 1906, out of every 1000 employees there were admitted to the hospital from malaria 821; in 1907, 424; in 1908, 282; in 1912, 110; in 1915, 51; in 1917, 14. The fatalities from the disease have fallen from 233 in 1906 to 154 in 1907, to 73 in 1908 and to 7 in 1914. The death rate for malarial fever per 1000 population sank from 8.49 in 1906 to 0.11 in 1918. Dysentery, next to malaria the most serious of the tropical diseases in the Zone, caused 69 deaths in 1906; 48 in 1907; in 1908, with nearly 44,000, only 16 deaths, and in 1914, 4.(*) But it is when the general figures are taken that we see the extraordinary reduction that has taken place. Out of every 1000 engaged in 1908 only a third of the number died that died in 1906, and half the number that died in 1907. (*) Figures for recent years supplied by editors. In 1914, the death rate from disease among white males had fallen to 3.13 per thousand. The rate among the 2674 American women and children connected with the Commission was only 9.72 per thousand. But by far the most gratifying reduction is among the blacks, among whom the rate from disease had fallen to the surprisingly low figure in 1912 of 8.77 per thousand; in 1906 it was 47 per thousand. A remarkable result is that in 1908 the combined tropical diseases--malaria, dysentery and beri-beri--killed fewer than the two great killing diseases of the temperate zone, pneumonia and tuberculosis--127 in one group and 137 in the other. The whole story is expressed in two words, EFFECTIVE ORGANIZATION, and the special value of this experiment in sanitation is that it has been made, and made successfully, in one of the great plague spots of the world.