PROFESSOR BATESON ON SPECIES.

Dominion, Volume 5, Issue 1384, 9 March 1912, Page 13

PROFESSOR BATESON ON SPECIES.

THE ORIGIN AND NATDEE OF .. TWINS. At the Roynljnstitution, London, on .January 23, Professor • Bateson gave , tho second of his course of lectures on Genetics, pushing his inquiry into the nature and origin of variation and difference in species into regions where the subject had ii human interest for members of tho audience who might not bo attracted by its purely scientific aspects. Alter a brief resume of his former lecture, he proceeded to a discussion of "m-sristic" as opposed to "substantiate" differences in species, taking, first differences of pattern and, primarily, pattern as produced by repetition. liepctition is as fundamental in organisms, lie said, as respiration or anything else. With a strong microscope we can see the process of repetition going on. Wo can see a cell divide. But what it is that is actually happening we have as yet no notion. Yet it is by repetition, or division, that tho process of heredity is carried on. The resemblance, of two brothers is a resemblance of symmetry: as the tiro parts of a divided cell resemble each other. Hertz had shown how an egg immersed in 6ca water freed from calcium ealta had a tendency to divide and become twins, and how this process of "twinning" could go on through many subdivisions. In Loeb's experiments as many as 90 per cent of eggs immersed for a few minutes in such water had "twinned." This has been shown to bo true of a number of species of organism. In human beings'twins arc of two kinds. With twins of opposite sexes who bear no greater resemblance to each other than ordinary brothers and sisters, it is probably a mere case of multiple birth, as in other kinds of animals. In other cases there appears to be an actual division of tnn samo egg into two individualities; when the two are almost precisely liko each other. The lecturer illustrated the point with a photograph of human female triplets, adult but still strikingly alike, and with a number of diagrams of the vnrious kinds of ways in which human twins are imperfectly divided—of which the Siamese Twins are the best-known example. It is to bo noted that twins are not, as it were, "rights and lefts." They are not two halves of the same thing, but the thing is reduplicated. The only detail, apparently, wherein a trace of "right and left is observable in human twins is in thumb-prints, Wilder having found several cases wherein, on! twins, the whorls on tho skin of tho thumbs of both hwuls turned the same way, that is, thev may be said to have the skins of two left (or two right) thumbs. This seems to imply a measure of control of one half of o, divided cell over the other half; but (lie fact that it only appears, so far as known, in this ono minute nnd superficial detail also shows that the control—and the right-and-left relationship-ceased at a very early stage. Such cases as the "magnesium embryos" of Stockard, in which by chemical treatment, the buds which should normally develop into two eyes were made to remain as one, and produced a one-eyed (Cyclopian) organism, and the case of the Cyrenean monster, are not properly cases of "coalescence," but of non-division. Professor Bateson concluded with a number of illustrations to show tho nature of abnormal repetitions or reduplications, as in the nostrils of a woman, the teeth of a fox, the nerves of n. cat, and tho bones of a horse'e foot, and, conversely, eases of non-division in pigs' feet nnd in human toes nnd fingers, and compared the general process of repetition of parts in nature to the formation of ripples on the sand. A reduplication wns not a ripple cut in two, but two ripples. So of a creature's scales or the vertebrae of an vetcbrnt© animal; nnd when wo understood this, ho snid, all the vast literature on what is known as "serial homology" became absurd, it being ns ridiculous to nrgne whether one vertebra (the seventh or Hie nth) "corresponded" to the samn vertebra in another species ns to argue whether Iwo particular ripples, in two sets blown nloiiif a bench, "corresponded" one with the oilier. It is a purely mechanical process, differing, hewever, from nny set of repetitions which we can as yet produce by mechanical menus in the fact that we cannot ill thn lntter, apparently, produce also ehwnicnl differences. He wound up with an appeal Io skilled physicists to come in nfid study natlenis in natural organisms,' lioliovinir that that, was likely to be a most fruitful line of investigation for Ihcni. Messrs. A. L. Wilson and Co. hare received instructions from tho Crown Laundry, Cihtminc Street, to sell by auction a laundry plant. The sale takes place on March 14, commencing at noon. Ifpssrs. Gumming and Son, Queen Street, Auckland, advertiso 021 acres of freehold land in the Wnikato district for sale. Particulars may bo had on application to th<i fluent. , !. For Bronolilal Cough, !*)» WoodV Great P»pcariniat Cons, la, Od, ,