INFLUENCE OF WHITE COLORS.
Prof. Wallace gave at Glasgow some curious speculations based upon the peculiarities observable in white animals. He had been discussing at great length and with rare knowledge the distribution of butterflies, remarking that some of the island groups were noticeably light-colored, and endeavored to connect their color with their environment as follows:
Some very curious physiological facts, bearing upon the presence or absence of white colors in the higher animals, have lately been adduced by Dr. Ogle. It has been found that a colored or dark pigment in the olfactory region of the nostrils is essential to perfect smell, and this pigment is rarely deficient except when the whole animal is pure white. In these cases the creature is almost without smell or taste. This, Dr. Ogle believes, explains the curious case of the pigs in Virginia adduced by Mr. Darwin, white pigs being poisoned by a poisonous root, which does not affect black pigs. Mr. Darwin imputed this to a constitutional difference accompanying the dark color, which rendered what was poisonous to the white-colored animals quite innocuous to the black. Dr. Ogle, however, observes, that there is no proof that the black pigs eat the root, and he believes the more probable explanation to be that it is distasteful to them, while the white pigs, being deficient in smell and taste, eat it, and are killed. Analogous facts occur in several distinct families. White sheep are killed in the Tarentino by eating Hypericum Criscum, while black sheep escape: white rhinoceroses are said to perish from eating Euphorbia Candelabrum; and white horses are said to suffer from poisonous food, where colored ones escape. Now it is very improbable that a constitutional immunity from poisoning by so many distinct plants should in the case of such widely different animals be always correlated with the same difference of color; but the facts are readily understood if the senses of smell and taste are dependent on the presence of a pigment which is deficient in wholly white animals. The explanation has, however, been carried a step further, by experiments showing that the absorption of odors by dead matter, such as clothing, is greatly affected by color, black being the most powerful absorbent, then blue, red, yellow, and lastly white. We have here a physical cause for the sense inferiority of totally white animals which may account for their rarity in nature. For few, if any, wild animals are wholly white. The head, the face, or at least the muzzle or the nose, are generally black. The ears and eyes are also often black; and there is reason to believe that dark pigment is essential to good hearing, as it certainly is to perfect vision. We can therefore understand why white cats with blue eyes are so often deaf; a peculiarity we notice more readily than their deficiency of smell or taste.
If then the prevalence of white-coloration is generally accompanied with some deficiency in the acuteness of the most important senses, this color becomes doubly dangerous, for it not only renders its possessor more conspicuous to its enemies, but at the same time makes it less ready in detecting the presence of danger. Hence, perhaps, the reason why white appears more frequently in islands where competition is less severe and enemies less numerous and varied. Hence, also, a reason why albinoism, although freely occurring in captivity, never maintains itself in a wild state, while melanism does. The peculiarity of some islands in having all their inhabitants of dusky colors—as the Galapagos—may also perhaps be explained on the same principles; for poisonous fruits or seeds may there abound, which weed out all white or light-colored varieties, owing to their deficiency of smell and taste. We can hardly believe, however, that this would apply to white-colored butterflies, and this may be a reason why the effect of an insular habitat is more marked in these insects than in birds or mammals. But though inapplicable to the lower animals, this curious relation of sense acuteness with colors may have had some influence on the development of the higher human races. If light tints of the skin were generally accompanied by some deficiency in the senses of smell, hearing, and vision, the white could never compete with the darker races, so long as man was in a very low and savage condition, and wholly dependent for existence on the acuteness of his senses. But as the mental faculties become more fully developed and more important to his welfare than mere sense acuteness, the lighter tints of skin, and hair, and eyes, would cease to be disadvantageous whenever they were accompanied by superior brain power. Such variations would then be preserved; and thus may have arisen the Xanthochroic race of mankind, in which we find a high development of intellect accompanied by a slight deficiency in the acuteness of the senses as compared with the darker forms.
AN INVOLVED ACCIDENT.
Though American recklessness of life is proverbial among foreigners, we may be thankful that India-rubber bags of explosive gases are not carried by ignorant boys through our streets, as in Newcastle, England. The practice resulted by a singular chain of mishaps in a violent explosion. The first error was in using a bag for conveying an explosive gas; the second in using a leaky bag; the third in the experimenter, who put coal gas into a bag containing oxygen; the fourth in sending a boy to deliver it. Then comes a chapter of results. The boy became tired and stopped to rest, dropping the bag on the pavement. Just as he did so a passer-by lit his pipe and threw the burning match down. By chance it fell upon the innocent looking bag, and probably just at the spot where it leaked. After the consequent explosion only two pieces of the bag could be found, one of which was thrown through the top windows of the bank. Even the sound wave, or wave of concussion, had a mind to distinguish itself. It entirely missed the first floor windows of the bank, and left them uninjured, though the windows in both the ground floor and the second floor were broken. The wave seems to have crossed the street, smashing the ground windows there, and then been deflected back across the street and upward to the top story of the bank.
AN OLD AQUEDUCT SYSTEM.
Ancient life is not usually considered to have been very cleanly, but it is to the credit of the Romans that as much as 2,200 years ago they made up their minds to reject the water of the Tiber as unfit to drink. They hunted for springs in the mountains, and in the course of a few centuries so many aqueducts were built that Rome had theoretically a better supply of water than any modern city enjoys. Practically, however, the Romans suffered from a peculiar kind of water pilfering. Instead of 400,000,000 gallons daily which the springs furnished, the city received only 208,000,000 gallons. This immense loss, says a careful paper by the Austrian engineer, E. H. d'Avidor, arose partly through neglect of the necessary repairs in the aqueducts, but still more through the water being positively stolen. For one of the principal favors by which the State and the emperors were in the habit of rewarding minor services was by granting concessions for the lost water; that is, for the water which escaped through the overflow of the reservoirs, cisterns, and public fountains, or through the defects in the aqueducts and mains. The consequence, of course, was that every landed proprietor who had obtained a concession for the waste water escaping from an aqueduct passing through his grounds was anxious to increase this waste as much as possible—and from this wish to intentional injury was but a step. The overseers and slaves in charge were constantly bribed to abstain from repairing damages which had arisen, or to cause new ones to arise, and these abuses reached such a pitch that one aqueduct (Tepula) brought no water whatever to Rome during several years, the whole having been wasted, or rather abstracted on its way. The irregularities of the water supply were still further increased by the nature of the mains and distributing pipes, which, as I have mentioned, were mere lead plates soldered into a pear-shaped section, incapable of resisting even the most moderate pressure and liable to injury by a common knife, so that any evil-disposed person could tap the main almost wherever he pleased. At a later period, indeed, the Romans appear to have used short clay pipes; lengths of such mains have been discovered, consisting of two-feet spigot and socket pipes carefully laid in and covered with a bed of concrete. These have outlasted all the lead pipes, and are still frequently found in good condition.