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Title
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Scientific. Science Notes.
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Description
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Australasian (Melbourne, Vic. : 1864 - 1946), Saturday 12 March 1898, page 52
SCIENTIFIC.
SCIENCE NOTES.
Ev PHVKCVE.
THE FKILL-OILLED FHAEJL
How little v.* Ldc»- of the Ssb inhabiting the ©pea f*ee«C; in spr.e of sJi the wvrk. .ha*
been dote bitbfcrio, i*» well Uuetratea by tbe caw of tii-s F;>Mts of shark. lie form if FtifLciemb" differ frt'ia tiiet of lie allies si bvixg to «:nke an ordinary observer at ljvt irlance,. fcno protista* f^Vl- Mould it to lte gltJDp to WliJCB it beloi.z*. TLe Wy is bus ana somewhat eeHike in fcrcn, and the tail imacad o* lurtlsg upwards m ordinary charts, is in the Kif.-.e Hue as the rest of the boar. Tbe B-caib it wot pkctd under the head
tut at ;Le etsd of the fnoui, wbik there t it only one firj ta tLe back, instead o: tue { nSni'ji-i present two in ox her j sharks. In T-siiet tiie uj/per ptrt of the
throat, or pharynx. is pkr«-d by a camber j ui which hi*: bordered by the gills, <iZ-d j tn v-rai^i jrill-riile- The gilk are very plen- j tifuUy -»ith blood-v«asek, eo that j the ilvsi it-' Kpread over a ha^e area, and
is separated fiom the water by thin JRem- J brane. TLiougb tLif- m^mbtane the wane. pa.*** of the body pass out, and the crygen dished ii; the wet*r is taken up b,v the blood. which i« thus purified. A current of water is constantly taken in by the mouth Slid parsed out through the giii-s'liu, &o that & Kuriicient eupplv of oxygen if enstir&d. In t «i«r jrreater nun'ber of sish of the pie»eni <iay the gill-siili- are roofed on each tide bv a cover, known at '.he opeiculum, so tfjat the dclicate gills are protect**! from the chance of enter -&1 injury. In the sharkfc this gill-cover is absent, so. that the giiltltte are plainly visible, and in most tharkfi
ere four in number. The frill-gilled shark j has *iz gil3-*4itf?. and these are each pro- j tected by a frill-like fiap of skin, and from j this character the ash Uxkee its tusrsie. The i teeth tre peculiar su form, and very cha- ] racteristic. FobmI forms closely allied to j the present sj»<rcies had loag been kBovn j froiii ancient rockf, but it wat supposed that j the :j i»e vrae quite extinct. Ojnwrtjueiitly j it wafe with great delight that the discovery j in Japaijese wateni wme years ago of this ^ ljvir.i' idbm1 was anrjOUDCed. Tben it was j captured near Sfadeira, and recently Pro-; fetfeor Oollert, of Chrit-iiaiiia, nai htate-i tliat j
the (same er^ecicfi has been taken off the j
coaet of Koniay. Ji is ttiange that bo re-; markable a form should occur in both the j Atlantic and. the Pacific attd have so^ Ions j I*»^ped no Joe, but it must Ix; remembered j that the chances of capturing an active fish ; iu a comparatively fcxuall and slowly-moving i deep-fcfca tiavil are remote, and we ui?ually i have to defend on the tireying of a rare;
specimen into fchallow waters, v.here it may j or may not be observed. j
KAUTHV'AKK STl llV A5TD ITS RRSJXTS. i The f)\K-uhii£ up of Japan to the influences J of western civilisation hag resulted in the j revolutionit-irjg of one branch of science, j Keiemologj*-the study of earth movement*j -ww more to scientific v.orkerr, European ) end native, in that countn' than to those of j B!1 the rart of the world. In .Japan the 1 Itfist form*: of apparatus for the investiga- j tion of cajiliqua'ke phenomena were gcada-j ally evolved, and the study of the record* s furnished by micb im?trumejit* bas led toj results of the bighett iriduitrial importance^ | In the fiifct place they thawed investigators [ the. necefgity for remodelling all their old
notion/; as to the nature of the earth movements. and the fresh id can on this point have led to new and better precaution* against diKit-ler. For many parts of the country the fccu-mologiht is now in a position to ttat'e the maximum force likely to act on a projected structure, anrl the direction from which the impulses may be expected to come, and buildingfi can be erected in such a wav BB to guard against tbem. Ae a result fiK-'h buildings-even those furnished with tall chimneys-constructed in accordance with the new ideas have been found to remain uninjured when everything round
them was Kbattered.
Borne experiments earned out on artificial earthquakes gave a hint which has proved invaluable to engineers and architects, for they showed that in any given area of ground the horizontal motion of the surface :fa greatest where the ground js softestmoreover,that themovementeare vervmuen 4ess violent at a distance underground. Some of the seismometers-as the instruments employed in earthquake registration are termed-have latclv been put to a curious use, in employing tnem to register the osculations of locomotives on railways. As a result, locomotives sent out from England Itave boil greatly improved in Japan by altering the balancing weights; in the» .changed conditions the oscillations bave become so slight as barely to affect the instruments. . This has resulted not only in increased comfort to the drivers, but also in » saving of coal, amounting to as much as from o«e to five pounds per mile run.
BKUttlKG FUB-8EMA
For many years considerable interest has been aroused in reference to the Behnng fur-seal. The great value of the skins has fed to their indiscriminate alaughter, and leara as to the extermination of the animal have been raised. The British and American nations, whicb are most interested in tee question of their preservation, appointed a commission of naturalwts to conttder the question, and from recent announcements it appear® that the members
,dve come to an agreement aa to the essen-, ial facte. Some time ago some regulations pere made, which were even then felt to be >f a mere temporary nature, and it was teen that, if the desired result was to be 1 icbiev-ed, more stringent ones would have ?. 0 bp framed. For the greater part of the i rear the seals Jive :in the open sea. but in ^ he breeding season they take to the land,
the young are unable to swim for the I month. There are at present two it herds, frequenting respectively the Btfiatidftr Islands off the coast of Asia,, lie Pribylov Islands, near Alaska. So tfliaa been the decrease in numbers
the past 25 years that, according to naricans, their hunting has ceased if commerciai valine, Tnc old males
and each selects -a. suitable spot. * " - h|iri»n. The young.
,^fad^ey settle in a tnain herd. Each of ronnd him about 16
lously against
Islands are idians fire de
land, and ig them at
males. their dsagiter ss far greater. It ». siid that pelapt sealing as ref^onsabte tor tbe drain of 30 per cent- of the yon»® man
Kuurtvioii, and 2: iE ecaredtv to be wonflma :
it ttisi an outcry iias beea rsisai again® j tbe practice. j
S7TLI-AB DISTAXCEE.
Hie e-lar syrtem in space may be com-j pared vo a Baliwuy idei in an ocean. ^ as4 , las ai? ik cist&noeE befweea die sun and, j the plaaete, they are quite insignificant as . 1 -compared ?n-Jtii those between tie sin an d, I evcsi lbe nearest of the fixed scare. It is; I not, therefore, surprising to find ? ! tlihu: whatever -vras known about stellarjdie- j
tenets till whhin the last sixty year£- im , method by -wiiieb the distance to be j j sought had b»ea laid down long oeiore, bat;
! inc: ntmpnl s <>I FujixCieot debcacy wttt not j
| available- Only n-ithin the i&Fi twenty. 1 years or so has the method been maae to j 1 yield results of more than a rough charsc-1 } now, ho-vrever, the distances ox sereral j j rjf f'jars can be stated vilh very con- j !dderable acc-crscy, Le., within one or twoj pgj- cent, of tbeir rcjue. asd those of a nnm
S ber of others caa be stated pretty closeiy. j 1 Tbe method by which tie investigation j ) is carried out may be explained eamewhst j 1 as follows:-.Stsjipoee two lines drawn from ; the star. one to the earth and the other to
! the stir: tbe angle -which the»e lines mate | I at the star njuet Then be measured, and j ! since the distance from the earth to the]
iua is known. the lengths of the lines can, be calculated in a similar way to that eta-] ployed by a surveyor in det«rmimag the distance of aa inaccessible object. Tbe difficulty arises pariiy from the extreme tmalines? of the angie to be measured, rjsnh from the fart that observations cancot be made at both ends of one base-line at the &ame time. What tbe astronomer
to do is to observe, a§ accunEtdy as *>o-f;bk. the manner in which the apparent 1 pos'tion of the star in the sty changes irom 1 month to month. Use earth being on one i «de of tbe eon, the star appears to be di£j placed a linle to tbe opposite tide of its j jrue position, as seen from tbe sun; the 1 change in the apparent position daring six : months amounting to twice the angle which ! the astronomer has to measure. At for tne j delicacy of tbis observation^ suffice it to j tav that the earth's orbit, if viewed from . the nearest fixed star, -would look about as i large as a halfpenny viewedty an observer ? three miles off. It is not very surprising, s to find that tbe nearest star-Alpha ! f'eiitauri. veil known as the brightest of] ' the two "Pointers"-was the first to have > I its distance measured: nor to find that thei ! result, as first announced, proved eubse- < I queutiy to be about 25 per cent, too large. 1 | One*of the most interesting phenomena; ! connected with the subject is the Etnallness j ' of the number of stare whose distances are \ ! susceptible of measurement. Twenty-five! ; millioDf of millicn£ of milee-the distance of ?
i Alpha Centauri-is itself a Email quantity ^ | 1 compared with tbe distances of tbe majority < I of the stare; concerning most of these, j I all that astronomers can tell us is that < ' thev are not less than a thousand millions ] } of millions of miles from us, and may be ? I anv amount further off than that.
j Few as are tbe stars whose distances have ? j been measured, nevertheless a comparison,
of their distance and brightness has given; i some interesting information. Some of (
the sun's nt-arett neighbours have ^ been j
! proved to differ from it very considerably m . 1 light-giving power; tbe closest star is a good , j deal more brilliant, the second closest many . times lens so tlian thfe sun. Our luminary,
indeed, appears to occupy an inferior position among the heavenlv bodies, its brightness being somewhere about one-twcntietu of the average, ae far as can be ascertained
at present.
THE SOLTH AMERICAS LO'G-FLSIL
Strand*^, as it were, in the fresib waters of a few parte of the world, tbe peculiar lung-fifft, which in former geological times were far more plentiful than they are todav, have managed to escape complete ex
termination- One of the charackristic!
features of fish is the fact that thw j breathe by means of gills, and the whole course of tne circulation of the blood is, 01 course, modified to this end. The higher groups, amphibia, reptiles, birds,'and mammals, are furnished with kings of greater or less complexity of structure, ranging from a simple bag like apparatus, in the frog to the highly complex one, say, in man. In all tbe groups, however, tbe young have, in at any rate the earlier stages of their development, a series of slits m the pharynx, similar to the gill fllitfl of a fish, and to these slits the blood supply w carried at first, just as it is through life _ in a fish. During tSie development of the higher forms a bag-libs outgrowth takes place from the throat, which ultimately gives rise to the lung. In a similar.way, in most fishes, a similar outgrowth gives nse to the swim-bladder. 80 tfhat a lung and a swim-bladder are, in their origin, the same tlinng, though they subserve different functions in the adult. In ordinary fab the swim-bladder has nothing to do with breathing; indeed, in manv cases, even, where it is large, it is a closed sac, the original opening into the throat having been shut permanently. When we reach the king-fish,
however, we find that the swim-bladder has; become more complicated. It is no longer, a smooth-walled bag, but is partly divided; into smaller chambers by projecting parti-: tioM, on which there is a plentiful supply of blood-vessels, and is, in fact, a simple, kind of lung. Thus the lung-fish has two methods of breathing, both by gills, like a fish, and by lungs like one of .the higher animals, ana so forms a connecting link be' tweea the two groups. Some zoologists
, clasB them with fish, while others prefer
to make a separate group of them. The "Burnett salmon," known to scientists as Cerafcodus, is a representative in Australia of the ancient group; another form is found in Africa, ana a third in South America. Our species appears to behave like a_ true fish -when the water ifl in good condition, but uses its lungs, coming to tbe surface . to breathe, when the prater is impure,
either from floods or during drought. Mr. Kerr, recently went to South America to study tbe habits of the form found there, fend to collect the eggs for' the purpose of observing-the processes of development. He - fojmd jthe animal, Lepjdosiren, plentiful in - -tiie swamps, wher6 it leads a sluggish exist
ence; wriggling slowly through the tangled growth". It rises regularly to tbe surface to'breathe, and feeds on water weeds and fresh-water snails. It burrows in the ground at the bottom of the swamp, and lines the; hole with grass, and here deposits its eggs., In its development it goes through stages very similar, to the frog. like the tadpole,
it has at first tufted external gills, and a: large sucker on its head. Later, on, as-in! the tadpole, these disappear, and the'per
manent gills grow, together with the lung, j During, the ary season it burrows In. the jiwd, keeping an air-hole open for tfa© piw* ? pose of breathing, '-.^heh'mtoP»w|!
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Date Issued
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1898-03-12
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Creator
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Physicus
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Publisher
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The Australasian
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Location State Territory
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Victoria
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Location Town City
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Melbourne
