As time went on and we found that we had freed the hospital grounds from mosquitoes, we began to replace the flowers and shrubbery which we had swept away in the early sanitary work. But we realized that we had to protect all vegetation from the ants; if we did not, it would be at once destroyed. While the methods used by the French for this purpose had been entirely successful and efficient as far as protection from ants was concerned, we could not use it on account of its mosquito-breeding qualities. The umbrella ant, in leaving its nest on its foraging expeditions, makes a very distinct trail some four or five inches wide between its nest and the tree to be attacked. Next morning, by following the trail, you can easily find the nest. Colonel Phillips, the superintendent of the hospital, found that by pouring a little bisulphid of carbon into the ant-hole, allowing it to vaporize for a few minutes and then exploding it, the gas would penetrate into every part of the nest and kill all the ants. In this way, all the umbrella ants around Ancon Hospital were killed off. At first it was very laborious, and took the entire time of one man, but in the course of time all the nests in the neighborhood were destroyed, and it is now only at long intervals that a new colony comes in and has to be killed off. At the present time the grounds are even more filled with shrubbery and flowers and tropical plants generally, than they were under the French, and they present as beautiful and attractive an appearance as can be found anywhere in the tropics. Entomologists tell us that this ant does not collect the leaf for food, but chews it up into a pasty mass, places it in the storehouses of its nest, and grows upon it a fungus which he uses for food. The food for this large hospital of over two thousand people was cooked in a large and airy kitchen, situated about the center of the grounds. This kitchen was equipped with every modern convenience both for good and economical cooking. Cooking by steam was used in part, and cooking on the range, for such things as were best prepared in that way. The food when prepared was sent to the various wards, the receptacles being carried in hand carts. The wards were so arranged that every two of them had a dining-room and diet kitchen in common. In each diet kitchen the heating apparatus was so arranged that the food brought from the center kitchen could be re-heated before being used. On a spur of the mountain near the center of the grounds was located the operating-room, with seven or eight surgical wards grouped around. This operating-room was erected by the French about the year 1882. We repaired the building and enlarged it somewhat. Dr. A. Herrick, the chief surgeon, equipped this building with every modern surgical appliance, such as x-ray machine, etc., etc. The results of the surgery at Ancon compare favorably with the results obtained anywhere else.