SCIENCE NOTES

Hokitika Guardian, 17 July 1926, Page 4

SCIENCE NOTES

(Froim, Science Service, Washington, U.S.A.) VAGARIES OF DISEASED PLANTS. The living tissue of plants .sometimes responds to the stimulus of disease, not by producing the characteristic diseased growths, but by producing normal kinds of tissue in the wrung place, according to Dr Erwin F. Smith, of the U.S. Department of Agriculture, who spoke before the annual meeting of the National Academy of Sciences. Dr Smith, who is an authority on the crown-gall disease of plants, injected some of the organisms that cause this nfilady into sunflowers. They responded by growing extra rays, or petals, in the disc of the sunflower head instead of around the edge, by forming cavities viuiin die plant, lined with the hair cells normally found on the outside, land by forming woody tissue in the pith, where normally nothing of the kind is lountl. Dr Smith points out these phenomena as striking examples of the effects upon voting growing tissue of changes in

in environment. Semi-nature tissue, he 11 savs, does not show such effects, d KIDDING BY SOUND. it- A “death-noise” instead of a ‘‘ilealh:c ray” was the phenomenon discussed a c.n April 28 before the National A<adli oniy of Sciences at Washington l),v •e Professor R. W. Wood and Alfred L. ir T.or.niis, of the .Johns Hopkins Univcr;e. sir.y. The “death-noise” would have n been inaudible to human ears, hut it If consisted of sounu waves just the same. 4 and it killed small fishes and other d aquatic animals in vessels ol water ;o in less than a minute. The two ro- ■- searchers generated exceedingly higlir- frequency sound Waves by means ol if electrical apparatus. The waves were ie prod need. at. a rate of from 100,000 to 11 4C0.0C0 to the second; the upper limit a of inaudibility to human cars is he-, l 0 tween 20,C00 and 30,000. It’ --a beam s of these sound waves is directed toe wards the surface of the water, TVofescr sar Wood stated, the surface is heiipod u)i in a mound. The vibrations heat t . the water, ft rise of nearly 10 degrees n Fahrenheit in one minute having keen recorded.

e lODINE FOR GOTTRE. lodine as a preventive of goitre is ,e. no new thing under the sun, acc-ord-e ing to Dr Gilbert 1). Harris, of Cori- mill University, U.S.A. In the cur,v rent issue of “Science” lie quotes from h an old Spanish- medical work by an early French scientist, Boussinganlt, who wrote in 1825. In one place the author states that, “till now, iodine is tlie only specific known lor goitre.” v Elsewhere, lie continues, regarding cors tain mineral springs in Columbia: “In s the province of Antioquia no other • salt is used, save that from these pee- ? uliar springs, whose waters 1 have analysed and convinced myself that, ? though thi' composition of their salts 1 is variable, there is in all an apprer risible ', lniount of iodine. Hence the reason that there is no goitre in An--1 tioquia : each inhabitant takes every f day a dose of iodine with tire salt he l consumes.” Again: “It is .a singular ■ fiiet that for more than a century ? these waters have been recognised as a sure specific for goitre.” • ' SEX DETERMINATION. An effort to determine the ftinda--1 mental differences between sexes has I been injade by studying bread moulds. - This group of t’uygi has distinctly sexual type of reproduction, but on ae- : count of the similarity in appearance I of the sexes it has been impossible to tell clearly which was male and which w;as female. Since the sex cells are ! equal in size and the developing off--1 spring are apparently nourished equally hv both sexes, these fungi are especially suited for study of this problem, Dr Albert F. Blakeslee, of the Carnegie Station for Experimental Evolution, as id in. a talk before the National Academy of Sciences at Washington on April 27. Investigations carried on by Dr Blakeslee and Miss Sophia Satina at the Genetics Laboratory at Cold Spring Harbour show that the females of the higher nlants make a more active response to bio-chemical tests tlisin males. 'Hie biochemical test to determine sox in humans, .made by mixing certain reagents with the blood, has been found applicable to plants,and over !>0 per cent of correct sex identifications have been made by this method. The bread moulds have been found to react chemically to these tests in the same way as the higher plants and animals, thus enabling the i researchers to nscret.niii which are male 1 and which are female.

HUMAN BODY GROWS TX THREE ; SPURTS. f Though a baby, or a small, boy, may i “grow like a weed,” bis growth does s not go on at a steady, unvarying rate. 1 but in three grand spurts, which over- t lap each other, making the “growth 1 curve” which scientists plot to measure c the rate into a very complex affair, q Dr Charles B. Davenport, of the Car- c uegio Institution of Washington, told of his studies of this problem on April r 27 before the annual meeting of the p National Academy of Sciences. The c first period of maximum growth rate j is right at the time of birth. The s i baby grows last, as everybody knows, e , hut the rate of growth falls off for J several years. Then it starts to speed ti nl> again, and in the ease of boys, at L least! it reaches a climax at about e < eight years—that embarrassing time e , when a fellow’s knees simply will not [, stay inside their proper garments. A t l second slowing down follows, and then ec a second speeding up. the rate of growth reaching its maximum at 15— fi (

the “all-hands-and-feet” period, when the youth is “shooting out of his shoes.” 'the three growth-spurts, Dr Davenport stated, correspond closely with periods of greatest activity of some of the internal glands. The first and second periods of growth correspond with activity on the pirt. of thyroid and pituitary glands respectively, whose .secretions are known to he growth-promoting. The third cycle, said Dr Davenport, is a fundamental one, underlying the others, and probably represents some more general gruwth stimulus exerted from the time of the first existence of life until growth stops altogether.