SCIENCE NOTES.

Otago Witness, Issue 2274, 30 September 1897, Page 48

SCIENCE NOTES.

• . ' It is a common knowledge that diseases have, as, a rule, their local habitations, says the Saturday Review. Some, like iropical animals and plants, live only in the tropics ; - some, like consumption, are gradually spreading over the whole earth ; others, like leprosy and smallpor, are gradually becom.ng limited in their distribution, and .may actually be tending towards extinction. Again, there are regions to which diseases have never reached. On the summits of high mountain ranges and in the circumpolar snow-fk-ldis the earth and air and water are as barren of the microbes of disease as thty are of animal life. Without question, if Nansen and his companion had been exposed to the same hardships and the same unsanitary conditions in these islands, the lowered vitality of their bodies certainly would have been unable to resist the continual bombardment of germs to which we ere all subjected. In a country like Britain, tbickly copulated for many centuries, and with the freest circulation of population, it cannot be doubted that every yard of surface contains the germs of the more common dieeas-ei 1 , and the native of some newer land, brought over here, falls a victim to our plague -6trickcn soil. By generations o? a destructive elimination we have beoome highly resistant to our native diseases, just as the Gold Coast .natives are less susceptible than we are to their own local diseases. But we are not fully protected, and cancer and consumption — tiwo of our common scourges — still take a large annual toll. It may be assumed that both arc due to -micro-organiems, the microbe : of consumption being well known, that of can oar being as yet only suspected. Probably no inhabitant of Britain escapes infection by the cancer organism ; carf-ainly none escaps infection by the microba of tubercle. Most of uf, fortunately, resist the intruders and are unaffected by the disease.

■ . • Dr F. E. Yoakhum, of Los Anodes, Cal., has (says the Scientic American) applied the X rays to the determination oi gold in qnartz. The physician was photographing a tumour ; there was a vacant space on the plate, and he placed a piece of gold-bearing qaartz on it ; when the plate was developed thß outlines of the rock came out on it, with spacka here and there, which showed the presence of gold. Since then he has taken a number of pictures of gold in valuable ore. The fluoroscope has been usad for- tbis purpose. It is believed that the discovery will- be of use to geologists and mineralogists ia prospectiug. • . • Mr David Paterson, of Roslin, Midlothian, has published in Nature the results he has obtained from experiments made regarding the effects of sunlight on the tints of birds' eggs. It is well known that many colouring matters are o£ the most fugitive kind, and that brilliant light is one of the most potent factors in their destruction. It would seem that ,the more delicate tints of birds' eggs are 61- this fugitive kind," some of ' the finest and most characteristic tints disappearing on much exposure to sunlight. Blue and greenish-blue eggs rapidly change under the influence of light, while little change is noticeable with darker-coloured eggs of olive-brown or chocolate shades. In the experiments referred to various eggs were halved lengthwise, and while one-half was kept in darkness for future comparison, the other half was exposed to direct sunshine in a glasß case for periods varying up

to 100 hours. These experiments clearly show that collectors should keep their treasures protected from Ught or their beauty will quickly fade. Mr Pateraon has tested various pigments for comparison with rhe tints on egg shells, and has come to the co&- : elusion tbat of water colours 60 per cent, are permanent, of coal-tar colours 30 per cent., and of egg-shell colours only 20 per cent, are fast. He might have added, however, that the water colours and coal-tar colours which are not reliable are perfectly well known to science, and can be judiciously avoided. • . * A novelty of interest to the careful housewife has recently been introduced. It i« termed an X rays egg-tester, and in construction is very simple, while performing its work in a highly satisfactory manner. The egg-tester consists of a small tin box fitted with holes to receive the egg.s. Underneath the eggs, on the foot of the box, is placed a mirror, and the light penetrating through the eggs is reflected there, so that the owner of the tester, by looking through a narrow (lit midway between the eggs and the mirror, can tell if' the said egg* are good, for when had the eggs beoome opaque and show dark in the glass. • . • Dr Morel is gradually building up a trustworthy mass of unbiassed facts on a most importaat pomt — the real relationship of crime to mental defect. We shall •"by-and-bye, by means of .such faefcs, be able to judge bot.wesn the schools of Lombroso and of the North. Morel makes the medicopsychological examination of each mentally-su-jpected prisoner according to a - most complete and uniform system, examining into bodily and mental heredity, into the dif=e<»ees of childhood, the education, the employment, the associations, and the temptations to which the pdsoner has bsen eub^ j«cfc. In addition, he "makes a careful psychological and an • exhaustive physical examination of the case. Ha says.- "By such means, I doubt not, crime and punishment will be 6tudied in a future time in a new way, and with tbis result — that the population of the prisons will diminish, and the very numerous yoang offenders between 18 and 25 to 30 years of age, b^ing really degenerate acd uneducated, will be taken to special institutions, where, instead of being imprisoned for a few months or a few years, they will rf oeiva a special education "till another medico-psychological examination declares them to bear the name of a good citizen." Tnis is a truly scientific way I of attacking a tremendous problem in which the human brain plays the chief part. We trust that in Great Britain we may in due time follow oa the same lines. We have done much in tbis country to aolve the problem of the light treatment of the criminal and fch» prevention of crime, but we have trusted hitherto to unaided common s«jnse and philanthropic feeling, rather de- v spising science ai d its teachings. We believe that tha science of medicine and the objective study of peycholf gy will be able in the future greatly. to aid trie legislator and the prison administrator in .this important matter — The Hospital. • . • Professor A. E. Verrill recently communicated to the American Journal of Science a valuable article on the subject of the colour that fish assume while asieep. In moßt cases the change consists in an intensification of the colours. The markings ; have a daiker appearance, and such modifii cation is of a nature to better conoeal the [ anical and render it. less visible during tha I right. In certain of the species observed by ! Professor Verrill the changes were more complicated. For example, the S-enotomus chrysops while awake and in a state of activity was silvery white, with iridescent plays of colour. At night it was of a dark brotz^s colour, and from this ground stood out dx transverse black bands. If it I cbanoed to be awikened from its eleep at night, in an aquarium, by the sudden turning on of the gas, so that the light was bright, the colour was instantly modified, j and the normal tints of the awakened animal exhibited themselves immediately. Here as&in the protective role of the colouration of the sleeping state is evident, since the animal sleeps among a'gse and the black bands are confused with the thalli and fronds, while the bronze colour closely resembles the greenish yellow colour common to many seaweeds. In the monacanlhus also the nocturnal colour ia very different. Tha animal is brown and greenish when it is awake, while when it is ' asleep its • body assumes a greyish colour which protects ie amid rocks and plants. In the cephalopoda, too, in the lollgo especially, the nocturnal colour is darker, and, in a general way, it may be said that the animal is less easily distinguished when asleep upon the rocky bottoms that it frequents than when awake. It is evidently well that this is so, since an animal too easily distinguished~by its colours or markings would become au easy prey during t,he*torpidity of sleep. • . • The penny-in-the-slot principle has j been- applied with success to the automatic distribution of drink?, and the system, which has been in vogue for some time on the Continent, has now put in an appearance in London and some other of our cities. The metropolitan establishments consist of an open shop, round which are arranged a number of ornamented cabinets, each cabinet having projecting t from its front two bent spouts, witli the name of a drink above each, a slot for the necessary penny, and a support beneath for a glass. An attendant washes tho glass after use, and replaces it in a rack ready for the next customer. The beverages are all of the temperance kind, but on the Continent alcoholic liquids are supplied in the earns manner. The mechanism for working the apparatus is simple in the extreme : the coin which is inserted in the slot actuates a cam, which causes a tap to be turned for a certain definite period, the time being regulated by the nature of the beverages supplied — for example, a tumblerful of hop ale or a wineglassful of ginger wine.

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