Swimming and diving, as one would expect, are greatly affected by the preliminary oxygen inhalation; the length of time during which submersion can be endured without discomfort is doubled, and the great effort of fast swimming rendered less rapidly exhausting. Cycling uphill at a rapid pace becomes, according to Dr. Hill’s own frequent experience, possible after oxygen inhalation when in ordinary conditions it was impossible. Hockey players and boxers he has found notably benefited by oxygen given both in the intervals of and after the exercise. It is, of course, to be expected that a wider practical application should be made of this simple method of increasing our power of sustaining muscular effort, and of enduring submersion. Dr. Hill suggests that the divers of the Mediterranean, who, without any apparatus, plunge into the shallow sea and remain below long enough to find, cut, and bring to the surface the valuable sponges of commerce, might use the method of preliminary inhalation of pure oxygen gas. He has also tried the method with a young racehorse, but owing to the fact that the course run was only a mile, and the animal perfectly fit and strong, he tells me that no advantage was found to result from the inhalation. With an older cart-horse somewhat tired by a day’s work—he obtained the most satisfactory results, the animal becoming obviously recuperated and working without distress.
The question has been raised as to whether the administration of oxygen gas to a man or to a horse when about to run a race should be considered as “doping.” It may perhaps be objected to by sportsmen, as involving the provision of special apparatus which all competitors would not be equally able to secure. But it is not “doping,” since that applies to the use of a drug, which, whilst exciting to violent effort, produces an injurious after-effect. Oxygen is not in this category; to take an extra quantity of oxygen into the lungs before starting on a race is no more unnatural or risky than to take an extra drink of water into the stomach or to swallow meat extract and such special preparations before or during a race. It would be interesting to see whether a runner in the Marathon race would (as Dr. Hill would expect) be greatly assisted if his trainer carried with him a supply of pure oxygen, and from time to time refreshed him with it. Football players might also be given oxygen at half-time; an oxygenated team would, one surmises, beat its uninspired competitors. A Fife team is reported to have done so. On the roads favoured by cyclists one may expect hereafter to find at the bottom of a long ascent hawkers of “breaths of oxygen” provided with gas-bags and calling out “Buy the lady a breff, sir!” It is, perhaps, worth noting that the relief afforded by oxygen-breathing is no less definite when the gas is taken immediately after a race or sustained effort than when used as a preliminary. The excess of choke-gas or carbonic acid formed during great muscular effort is not the principal cause of the distress experienced. That gas is thrown off by increased expiration. It is the using up of the oxygen and the insufficiency of the supply in the atmospheric air inspired that causes, under these circumstances, giddiness, exhaustion, and often collapse.
The difficulty in breathing and the prostration experienced by many people in mountain-climbing is largely due, not merely to the muscular effort of climbing, but to the fact that the rarefied atmosphere at heights of 8000 ft. to 15,000 ft. and more gives into the lungs in every inspiration but a fraction of the oxygen which is inspired at low levels, and moreover, owing to the low pressure, much less is held in the blood. Even when conveyed by mule, cog-rail, or balloon to these heights—and, therefore, without muscular exertion, sensitive people suffer severely from temporary “oxygen-starvation.” They as well as the laborious mountaineer could be saved from all such inconvenience by the use of a skilfully-constructed “traveller’s flask” of oxygen gas.
The observations and experiments as to the possible use of pure oxygen by athletes suggest that we might all benefit by occasional if not frequent use of such an atmosphere. Indeed, there are some individuals—amongst others a well-known and distinguished actor—who before making some special effort, or even when feeling tired and unequal to their daily work, inhale under medical supervision a certain quantity of oxygen gas. It would certainly seem that since country air, sea air, and mountain air are useful and refreshing, an artificial supply of extra oxygen might be inhaled in London, either in one’s own house or in establishments provided for the purpose, with definite benefit to health, especially if the inhalation were combined with exercise.
The experiments made by Dr. Hill have come about in connection with work undertaken for the purpose of improving the diving and life-saving apparatus named after its inventor, Fleuss. This invention consists essentially in a water-tight helmet and jacket connected with a cylinder of compressed oxygen gas which is carried by the diver. The advantage of such an arrangement is that the diver is free from pumping apparatus and can go where an ordinary diver could not. Mr. Fleuss was able, by diving with this apparatus, to prevent an immense loss of property by arresting the flooding of the Severn tunnel which was imminent during its construction. A difficulty in regard to the Fleuss apparatus has been that oxygen gas is a poison, causing inflammation of the lungs and convulsions when under a pressure of from two to three atmospheres—that is to say, at from 30 ft. to 60 ft. depth in water. The pressure exercised by the air of the atmosphere at sea-level is equal to that exercised by a column of water 30 ft. high, and hence at 30 ft. depth in the sea the oxygen gas would be under the pressure both of the atmosphere itself and of water to the same amount—which is expressed by saying that it is under two atmospheres’ pressure, or twice the atmosphere’s pressure. The pressure of the atmosphere is, in plain figures, 15 lb. on every square inch of surface. Of course, the oxygen is compressed far beyond this point in the cylinders in which it is carried. In using it, it is allowed to escape by opening a valve leading into an elastic sac, and is then and there subject to the pressure depending on the depth of water to which the diver has descended. It is found to be dangerous for a diver with this apparatus to descend to a depth of more than 30 ft. having pure oxygen in his apparatus, because the oxygen is then compressed under a pressure of two atmospheres. Accordingly, Dr. Haldane, of Oxford, has proposed that the oxygen should be diluted with atmospheric air, so as to give a mixture of equal volumes of oxygen and nitrogen. With this mixture the diver can safely descend to a depth of 60 ft. The apparatus is provided with a partition containing caustic soda, which absorbs the carbonic gas thrown out of the lungs in expiration. With such an apparatus a diver can safely remain under water at a depth of 60 ft., and walk about and explore for as long as two hours. A most important application of this self-contained diving apparatus is found in its use in the exploration of mines, where smoke or gaseous products resulting from an explosion render it impossible for rescue parties to penetrate without its use. It has been the means of saving many lives in such circumstances. A form of this apparatus is made in which the oxygen is supplied, not by a cylinder of compressed gas, but by granules of a chemical compound called pneumatogen, a peroxide of sodium and potassium, which when breathed into absorbs carbonic acid from the air expired by the lungs, and gives off pure oxygen. Submarine ships are now being provided with a dress or outfit of this description for each member of the crew, so that in the case of the entrance of water into the submarine, every man can put on his “oxygen helmet,” and one by one, when the ship is full of water, they can pass out by the conning tower and float to the surface. The perfected diving dress, with self-contained diluted oxygen supply and other improvements, has been constructed by Siebe, Gorman, and Co., and was exhibited by Dr. Leonard Hill at a soiree of the Royal Society.
[XXVIII]
SPARROWS, TROUT, AND SELECTIVE BREEDING
The talk about the urgent need for the destruction of sparrows reminds me that the word “sparrow” is applied commonly in this country to at least two very different but common birds. No doubt farmers and gardeners know well enough the house-sparrow (Passer domesticus or Fringilla domestica of Linnæus), which is the one they consider injurious. But some boys and some newly-fledged proprietors of country places may inadvertently confuse the house-sparrow with a very different bird, though only a little smaller and of a general brown colouring, also called “sparrow,” namely, the hedge-sparrow (Accentor modularis).
The hedge-sparrow is a true denizen of the country. It does not live on grain, but on insects and grubs, and is useful on that account to agriculturists. Its eggs are pure blue. A spotted egg of a cuckoo laid amongst them readily catches the eye, so that cuckoos’ eggs are often found in hedge-sparrows’ nests. It seems that it is all a mistake on the part of the cuckoo hen when this occurs. The strain of cuckoos properly attached to hedge-sparrows lay a beautiful blue egg differing only in its somewhat larger size from those of the hedge-sparrow itself, and hence difficult to detect. These blue cuckoo-eggs—proper to cuckoos which make use of the hedge-sparrow as foster-mother—escape detection both by boys and the foster-parents, and successfully hatch out and propagate the race of blue-egged cuckoos with a memory and a sense of smell which bring them back if they are hen-birds to the little hedge-sparrow’s nest when they are grown up and have an egg to dispose of. The spotted grey or brownish eggs are, if not discovered by boys, ejected (there is reason to believe) by the hedge-sparrows themselves. They were deposited by mistake by some pippet-loving or warbler-seeking strain of cuckoo in a hurry, or are throw-backs to a common ancestral colouring of the egg due, perhaps, to the male parent not being of the true blue strain. A very fine series of “clutches” and nests of hedge-sparrow, robin, shrike, reed-warbler, pippet, yellow-hammer, and other birds with the accompanying cuckoo’s egg may be seen in the Natural History Museum, and they show how closely the parasitic egg often resembles that of the foster-parent, though striking failures also occur.