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Photo by Louise Birt Baynes THE DAINTIEST GUEST

A picture of an inquisitive and very puzzled humming-bird probing an artificial flower

lish sparrow, house-finch, tree and violet green swallow, purple martin, housewren, Parkman's wren, Bewick's wren, Vigor's wren, and Texas Bewick's wren, white-breasted nuthatch, tufted titmouse, black-capped chickadee, Oregon chickadee, Carolina chickadee, robin, and three varieties of bluebirds-eastern, western, and mountain. To this list the Carolina wren ought probably to be added; though while I do not know personally of any record of its actually building in a birdbox, it builds about houses and in the most unheard of and crazy places.

Robins and phoebes may be encouraged by shelves conveniently placed beneath the roofs of porches, piazzas, and sheds, while the insect-eating barn and eave swallows may often be helped in their choice of nesting sites by a supporting shelf. Vines on trellises or about the piazza posts are attractive nesting sites for chipping sparrows, as well as robins, and I once knew of a bluejay that built in a wistaria vine overhanging a friend's front porch.

One can never tell just what birds are going to do. Crows are reported to have nested in one of the squares in the city of Philadelphia and on Beacon Hill in Boston, while a pair of sparrow-hawks have bred beneath the eaves of the Lawrence Scientific School in Cambridge, Mass.

Chimney swifts should also be encouraged, and when possible the chimneys

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Photo by Ernest Harold Baynes

This is a photo of a wild chickadee feeding her young in June. She does not fear in summer

the hand that feeds her in winter

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should be warned that if their cats are caught trespassing they will be turned into fertilizer.

Red squirrels are next on the list and should be shot on sight, but I have never found the depredations of the gray squirrel to warrant similar treatment. Birdchasing dogs are a nuisance and should be restrained during the breeding season.

Skunks and foxes should both be discouraged, and the wily raccoon and elusive weasel also, if perchance they are found to lurk about.

Of the hawks, the cooper and sharpshinned hawks should both be shot at sight, while of the owls, the great horned is incapable of reform. The little screechowl is almost always beneficial on account of the numbers of mice it often de

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THE NATIONAL GEOGRAPHIC MAGAZINE

stroys, but individual screech-owls are often destructive to bird life.

Crows and jays will bear watching, There seem to be good crows and jays, and then again individuals among them of exceeding bad habits, as many a longsuffering bird family knows to its sorrow. In many places the English sparrows are pests and should be shot and trapped relentlessly. They are pretty canny birds, and if once they learn you are after them with a gun they quickly desert

the premises. If owing to surrounding. conditions gunning for them seems undesirable, traps may be used with telling effect. There are several kinds in use in this country.

Last, but not least, the black snake should be killed whenever found; its large size, great activity, tree-climbing propensities, and taste for eggs and small birds have fairly won for it the reputation of being one of the birds' deadliest enemies.

REDEEMING THE TROPICS

BY WILLIAM JOSEPH SHOWALTER

Author of "Battling with the Panama Slides," "The Countries of the Caribbean," "The Panama Canal," in the National Geographic Magazine

I

N THESE days when medical science has been recording one triumph after another over germ-produced diseases, when the germ-hunter in his laboratory has been ascertaining the causes of so many mysterious afflictions and laying the foundations for one preventive measure after another, people all but lose sight of the tremendous debt humanity owes to the expert in experimental medicine and the sanitarian. Indeed, he would be a prescient mathematician who could calculate what the vast amount of this debt is.

It is only when we look back over the records of the past, when civilization was young and humanity without knowledge of the causes of the great epidemic diseases, that we can have a faint appreciation of what the patient man of the microscope has wrought in humanity's behalf.

When we see Naples, in the seventeenth century, as helpless as a new-born babe in the grip of a plague during which 380,000 souls perished in six months; when we see Constantinople, in 1812, with 144,000 deaths; when we see London, in the days of the great plague, with 70,000 of its population carried off ; when we go back to China and behold a few short years in the fourteenth century with a "black death" mortality record of 13 mil lion souls, and to Europe, in the great

Scourge of 1347-1350, and see 25 million people dying; when we come on down the years and see the untold millions who have died from the numerous pestilences which have inflicted death upon mankind; then, and not till then, can we begin to appreciate what it all means.

Even then our appraisal will fall far short of the truth, for in those times the world was, in a sense, larger, the seas were broader, and the distances on land much greater than in these days of highly developed transportation and commerce. How can the mind conceive of the terrible toll epidemic diseases would take today, with our world-wide commerce, with our metropolitan and cosmopolitan cities, and with the constant commingling of the peoples of all lands, were it not for preventive measures?

MAP-CHANGING MEDICINE

Throughout the history of the ages one may read of great changes in the maps of the earth that have resulted on the one hand from the ravages of disease and on the other from the discovery of methods of combatting it.

We see the "glory that was Greece" depart because of the terrible toll exacted by malaria; we see a Panama Canal made possible because of the knowledge of the causation of yellow fever that came to

REDEEMING THE TROPICS

us through the patient and heroic work of a group of army surgeons; we see cities like Havana and Rio de Janeiro transformed from pest-holes into municipalities where epidemic diseases are under control.

Today thousands, nay millions, of human souls living between Cancer and Capricorn are being freed from the thralldom of those terrible visitations that came periodically only a few years ago. Africa is rising up against the terrible sleeping sickness and the insidious malaria that have made it the "Dark Continent" for generations without number.

Wherever we turn we find places where once a man gambled with death when he visited them being converted into regions where good health conditions exist. Preventive medicine everywhere, and in the tropics in particular, is writing a new geography of inhabitable territory and of commercial opportunity.

Where yesterday the barriers of disease were up against the peaceful and resource-developing invasion of capital and enterprise, there today is found health and happiness and prosperity. Where yesterday a man going to the tropics, even for a short stay, was bidden good-bye by his friends as one who stood an even chance of never returning, today men and women go there for long periods; and in some places are quite as safe as at home, and in hundreds of others only a little less so.

HOW IT ALL HAPPENED

Truly the story of how all this has been brought about is the world's most splendid exemplification of the proverb that truth is stranger than fiction. For hundreds of years man stood helpless and appalled in the face of the onset of great epidemics. He saw millions of his fellow-beings visited with deaths more horrible than ever torture chamber could invent, but not knowing whence the affliction came or whither it went. He surmised and guessed, and finally saw a certain relation between dirt and disease, and gradually the elimination of dirt. checked the ravages of some epidemic diseases.

Then came the microscope with its discovery of infinitesimal worlds, and with

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it Pasteur and his discovery of the relation between bacteria and disease. One by one new germs were discovered, and soon medical men came to understand the methods of the transmission of most of the epidemic diseases of temperate climates.

Still no one knew the cause of the epidemic diseases most characteristic of the tropics, and without this knowledge no satisfactory superstructure of preventive tropical medicine could be reared. Tropical humanity was attacked by myriads of enemies so subtle that men did not know even that they existed, and yet so terrible that the carnage of the world's battlefields paled in comparison.

For centuries on end men had been seeking after the truth of the causation of yellow fever, bubonic plague, sleeping sickness, and allied diseases. Some of them had nearly guessed it. Sir Henry Blake tells of having seen a medical work in Ceylon, some 1.400 years old, which charged the mosquito with being a carrier of malaria. The word canopy itself was brought into the language from a Greek word meaning gnat.

WHY THE CAT WAS WORSHIPED

There were many strangely close guesses at the cause of disease in the early history of the human race. Far back in Egyptian history the people came so near to guessing the cause of plague that they made the cat a sacred animal. They noticed that where there were cats there was no bubonic plague, and if they had only stopped to think a little further they might have seen that where there were cats the rats were scarce. But this relation did not strike them, so they went on worshipping the cat, and thinking that it was the animal's supernatural power that saved them from contracting plague.

The honor of having written the first modern work charging the mosquito with being a responsible agent in the spread of yellow and malarial fevers belongs to an American, Dr. Nott, of Mobile, Alabama. In 1848 he published a treatise. upon yellow fever in which he charged the mosquito with the crime of spreading these diseases. A little later Dr. Louis Beauperthuy, studying an epidemic of yellow fever in Venezuela, also laid the

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FIGHTING THE PANAMA MOSQUITO WITH OIL

These sanitary drip-barrels automatically spread oil, drop by drop, over pools, streams, and marshy places, thereby preventing the mosquito from breeding in the water. "He (Ross) proved beyond any peradventure that the Anopheles mosquito is the intermediate host, and that no one can contract malaria except he be bitten by a mosquito which has previously bitten a person suffering from that disease" (see page 347).

blame upon the mosquito, and charged that it introduced a poison similar to snake venom into the human system through the biting process.

Step by step a closer approach to the truth was made, and in 1883 Sir Patrick Manson demonstrated that the mosquito was the intermediate host of the blood parasite filaria.

But it was not until Sir Ronald Ross arrived upon the scene with his investigations that the real truth of the principle of insect-borne diseases came to be understood. Prior to this Laveran had succeeded in isolating the germ of malaria; and, building upon this foundation, Ross labored to ascertain the exact relation between man and the mosquito.

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