National Geographic : 1978 Feb
with the Canal Zone Government, notes that in 1949 the island's population of howler monkeys dropped by 50 percent. (It now stands at 1,300.) "The cause was yellow fever," says Dr. Gale. "That was the only time in fifty years that yellow fever had crossed the canal. The deaths of the howler monkeys warned us." 1418 HOURS. Alongside buoy 62. Passing clumps of water hyacinths. Dick advises skipper, "We'll soon be in Chagres River. Poor water there." We are approaching the cut known to ex cavators as Culebra and renamed to honor the engineer David Gaillard. Yet the greatest challenge in building the canal was not en gineering, but medical. During the railroad- construction days, yellow fever and malaria provided the isthmus a ghastly export: cadavers preserved in barrels of alcohol for medical schools. During the de Lesseps era, the same diseases took some 20,000 French lives, dooming their project. Not until after Dr. Walter Reed's experiments with mos quitoes in Cuba following the Spanish American War did Americans possess the medical skills to build the Panama Canal. Even then one man complained of "mos quitoes so thick I have seen them put out a lighted candle with their burnt bodies." The job of mosquito control is never fin ished. Last September, for example, the 10 year-old son of a U. S. serviceman at Howard Air Force Base came down with the zone's first case of malaria in four years. "We beefed 293 Camouflaged by mud, a soldier of the U. S. Army's 101st Airborne Division slith ers through the jungle-warfare course (left) at Fort Sherman. Treaty critics claim the canal will not be adequately defended. Ad vocates argue that it is indefensible against sabotage anyway. The military deems the canal important for transport of troops and supplies. More than 1,500 Government ships passed in 1968 at the peak of the Viet Nam conflict, compared with 85 in 1976. All U. S. Navy vessels can fit in the locks except 13 of the largest aircraft carriers, as shown by a superimposed outline (above). Modern supersize oil tankers likewise won't fit.