Recent scientific work, discovery, and application to practical affairs of the results of discovery, in regard to three great obstacles to human life and prosperity illustrate the vital importance to the state of scientific research. The obstacles in question are the diseases known as malaria, yellow fever, and Mediterranean, or Malta fever. It is now twenty-five years since Dr. Laveran, of Paris, discovered that malaria, or ague, is caused by a very minute parasite which exists in the red blood corpuscles of those stricken with the fever, and suggested that it is probably carried from victim to victim by blood-sucking mosquitoes (gnats). Major Ross, of the Indian Army, who has been rewarded for his discovery by the Nobel prize, determined to find out what gnat it is which carries the malaria-germ from man to man, and by most persevering experiment and microscopic examination showed that it is not the commoner gnat or mosquito (Culex), but the spot-winged kind (Anopheles), which alone can spread the malarial infection. But Major Ross is, before everything else, a medical man, and his great purpose has been to apply his discovery to the prevention of disease.

Whole regions of the earth’s surface are rendered dangerous, or even uninhabitable, for civilised men by malaria; in other words, by the Anopheles mosquito. Accordingly, Ross set to work to find the best means of destroying these agents of disease. He found that the Anopheles gnat breeds in natural collections of water lying upon the surface of the ground in open country, and not as many common varieties of gnats do, in vessels and cisterns in houses. The pools frequented by the malaria-carrying gnat are small and easily drained. The obvious direction of science, therefore, was to remove or to cover up these pools wherever they were found in the neighbourhood of human habitations. Although Major Ross made his discoveries in India, and although he opened a campaign against malaria by removal of surface pools in the Colonies of West Africa—“the white man’s grave”—twice visiting the chief British settlements—only half-hearted, incomplete measures have been taken, insufficient funds have been expended, and a supine executive and half-incredulous officials have failed to do more than partially reduce the prevalence of malaria in those regions. On the other hand, where intelligent officials have understood and accepted the clear results of science in regard to malaria, the most striking and satisfactory consequences have followed.

At Ismailia, on the Suez Canal, malaria was almost universal; in 1866 there were in a population of eight thousand, 2,300 cases. In 1897 there were over 2,000, and in 1902, when Ross was asked by the Prince d’Arenberg to visit the place and advise as to measures to be taken, there were 1,551 cases. Ross directed the filling up of the breeding pools. The marshes were filled up with sand, the irrigation channels were deepened or treated with kerosene oil (which spreads as a fine film, and chokes the gnat larvÆ), and the cess-pits were rendered uninhabitable by chemical treatment. In one year the cases of malaria fell to 214, in 1905 they were only thirty-seven, and now the Suez Canal Company officially reports, “all trace of malaria has disappeared from Ismailia.” The same satisfactory results have been obtained in Port Said, in Khartoum, in Port Swettenham of the Federated Malay States, in Havannah City, in Panama, and, in fact, wherever intelligent conviction has led to the active and complete employment of the methods necessary for the destruction of the gnats. Under the British Government of India and the African and West India Colonies, little has been done. Why? Because of the handmaiden theory and the ostrich-like refusal of our officials to face and accept the master.

An even more wonderful and beneficent result has been obtained in the case of that terrible disease “Yellow Jack,” or “Black Vomit”—the yellow fever. Owing to the discoveries and definite proof by Ross as to the part played by gnats in malaria, the able medical men in the public service of the United States of America have thoroughly examined experimentally the mode of infection of human beings with the germ of yellow fever, and have conclusively proved that infection is solely and entirely due to the bite of one species of gnat—the Stegomyia fasciata. They have proved to absolute certainty that yellow fever is not carried through the air, nor by food or drink, nor by contact with infected persons or their cloths or emanations, but only by the fasciate gnat, a house-frequenting species, which sucks the blood of a yellow fever patient, and after twelve days, and not till then, becomes capable of imparting the infection to those whom it may stab or “bite.” The firm demonstration of this fact was not made without great devotion, courage, and self-sacrifice. In the ardour of their pursuit not a few of the experimenters risked and lost their lives. Among these the name of Dr. Lazear, of the United States Army, is prominent. He deliberately permitted himself to be bitten by a stray mosquito in a yellow fever hospital, in order to show that the insect could convey the infection. He was bitten on Sept. 13, 1900, and died on Sept. 25, having proved his point.

The actual germ, microbe, or minute parasitic organism which causes yellow fever, and is carried by the fasciate gnat, has not yet been detected. Nevertheless, without seeing and isolating the microbe, the medical men of America (Sternberg, Finlay, Carroll, and others) have, by destroying the gnat and preventing its access to men—especially to patients already infected, and, therefore, certain to infect the gnats and cause them to spread the disease—practically made an end of yellow fever in many great cities of the New World, where it was only six years ago an ever-present horror, striking men down with a suddenness and with a deadliness which paralysed human activity. Here, as in other cases, intelligent appreciation of the results of science by a governor or a municipality has saved thousands of lives. On the other hand, in Rio de Janeiro, “the opposition encountered by the sanitary authorities of the city from political factions and the ridicule to which they were subjected by the local Press” were insuperable (I quote from an official report), and so a few more thousand lives were sacrificed before the master was recognised and the proffered safety accepted. In Vera Cruz, in New Orleans, and in Panama yellow fever has been reduced to a vanishing quantity by removing the pools and tanks in which the fasciate gnat can breed, and by making use of wire-gauze to prevent the access of mosquitoes to houses, bed-chambers, drains, and baths, and especially to prevent not only their access to, but their egress from, the rooms and beds of patients already infected with disease.

In the city of Havannah, during the American occupation of Cuba (1900-1903), Colonel Gorgas reduced the death-rate due to yellow fever from an annual average of 751 to so small a figure as six. The same energetic and faithful administrator has been at work, with even more remarkable results, in the canal zone of the Isthmus of Panama since 1904. The attempt of the French to cut the canal was foiled chiefly by yellow fever and malaria. It is estimated that their effort cost quite 50,000 lives. Assisted by an able and enthusiastic staff, and charged with the task by a Government which comprehends the fact that the really “practical men” are the men who recognise science as the master (not as the negligible eccentric handmaid), Colonel Gorgas has banished the mosquito from his zone of occupation. As a consequence there is neither malaria nor yellow fever on the Panama works. In 1906 the total death-rate amongst 5,000 white employÉs on the Panama Canal works was only seven in the thousand. Further, in last April the daily sick-rate of the total force of about 40,000 people was only seventeen in the thousand. Colonel Gorgas declares that there is but little sickness of any kind among the Americans in the employ of the Panama Commission, and that they and their wives and children are fully as vigorous and robust in appearance and in fact, as the same number of people in the United States. There is no reason why the centres of wealth, civilisation, and population should not again be in the tropics, as they were in the dawn of man’s history.