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3d. This prolongation appeared to takeplace after a very long time. I should add,that the extended filaments were not inthat iegular juxtaposition which is re-

marked in the nervous chords ; they were,on the contrary, separated, as if they werewith difllculty traversing the interposedsubstance.

.

For an account of what has been doneprior to these researches of M. 1revost, werefer our readers to the foreign articles inthe 185th Number, Vol. XI. of TjiE LANCET.

Modus operandi nf Belladona on the Eye.M. Segalas read a paper before the Royal

Academy of Medicine in Paris, on the man-ner that belladona acts when applied to theeye. Having placed on the eye of a youngcat a grain of the extract of belladonna, hesaw the dilatation of the pupil begin fourteenminutes afterward. Having, in a secondexperiment, placed a grain on the pleuraof a cat of the same age, and the same

height, he saw the dilatation return eightminutes after. Lastly, in a third experi-ment, having injected a grain into the bron-chial vessels, the dilatation appeared two’minutes after, that is to say, seven timesquicker than after the direct application ofthe substance on the eye. It would seem,then, says M. Segalas, that the dilatation ofthe pupil is quick in proportion as the bel-ladonna is applied to a surface possessing agreater or less degree of absorbing power,from which it would result, that the bella-donna only acts on the eye after being ab-sorbed and carried by the blood to this or-gan. He adds, as another proof, that thebelladonna, which is only applied to one ofthe eyes, manifests, nevertheless, its actionon both at the same time.MM. Renauldin and Orfila made a few

observations on this subject. The formerwished to know, how long the dilatation ofthe pupil lasted ; he saw in one case, wherethe belladonna had been applied, the powerof this substance continue thirty-six hours.The dilatation continued just the same timein M. Segalas’s experiment. The latter(M. Orfila) stated, that hydrocyanic acid

applied on the eye kills suddenly, and muchquicker than when applied on any other

part ; moreover, death follows so rapidly,that it is difficult to believe that the poisonhas been absorbed. In the numerous toxi-

cological experiments which Mr. Orfilatried, belladonna was one of the substances,it was applied to the skin, the cellular tissueand the various organs. The pupil wassometimes dilated, at others contracted, and’in certain cases it remained insensible ; but Iit constantly became dilated when the bella-donna was directly applied to the eye.

ZOOLOGY.

On the Habits of the Ornithorynchus.*IN a late number of the Anthologia of

Florence (Dec. 1836), M. Gregori has pub-lished the following observations on thehabits of the ornithorynchus. " The ornitho:rynchus inhabits the marshes of New Hol-land ; it forms among the tuft of reed onthe borders of the lakes, a nest composedof brushwood and different roots, interlacedamong each other; in this it lays twowhite eggs, smaller than those of ordinaryhens’ eggs ; it sits on them a long time,and in the same way as birds do theirs, andnever leaves them unless menaced by someformidable foe. It appears, that during thistime, it eats neither seed nor herbs, but con-tents itself with the mud or mire close toits nest, and which suffices to nourish it ;at least, this is the only substance found inits stomach. When the ornithorynchusplunges under water, it rests there but ashort time, and comes to the surface, mov-ing the head in the same way as ducks do. Ittraverses the sides of the marshes with

great rapidity ; it is very alert, and is verydifficult to take, on account of the excellence

* Ornithorynchus Mandibulæ rostratæ

(anatlna?) Dentes nulli t. ’

0. Paradoxus. The duck-bill. Ger. dasSchnabelthier. (Abbild. Nat. Hist. Gegenst.Tab .11.)

This extraordinary creature is distin-guished from all mammiferous animals yetknown, by the unprecedented formation ofits jaws, which resemble in the closest pos’sible manner, the broad flat bill of a duck,are covered in the same way with a softmembrane, plentifully supplied with nervesfor the purpose of tasting, and also, like it,serrated at the lateral edges. The feet areprovided with webs, which, in the frontones project beyond the claws, and by thatmeans can be folded up or expanded like afan. No appearances of teats have beenhitherto detected in either sex. This won-derful animal lives near the lakes about

Botany Bay, in the fifth part of the world,so rich in creatures of remarkable formation.Vide Blumenbach’s Natural History byGore, a book which we strongly recommendto the younger part of the professi,on.-

+ For the organs which Sir E. Home has d.e-scribed as the molar teeth, and which neither pos-sess euarael nor bony substance, fangs noralveoli; thestructure of which too,he has compared with that ofthe inner membrane of the gizzard in fowls, cannot,according to the scientific terminology of anatomyand natural history, be considered as actual teethof a warm blooded quadruped.

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of its vision. It-only employs one nostril tobreath through in the air, which might leadone to think that the other is only used whenthe animal is under water. It scratches thehead and neck with one of its hind feet, inthe same way as dogs ; it endeavours to

bite when taken, but its beak being veryflexible and weak can do no mischief. Themale alone is supplied with a spur on thehind leg, and this it employs against agres-sors. The wound which it inflicts producesinflammation and a very severe pain, butthereis no instance of death being produced byit."—Antologia di firenze, tom 24, p. 305.We regret that this work, say the editors

of the Annales, usually omits to state fromwhat source it derives the curious factswhich it communicates to its readers. Thesewhich have been just mentioned bear a re-semblance to an account of Sir Patrick Hill,printed in the 13th volume of the Trunsac-tions of the Linnæan Society of London,p. 622 ; but they are rather more precise,which leads us to suppose, that they are de-rived from another source.

We will just quote an extract from theanswer of Dr. Southwood Smith, to M. Ed-wards, in reference to some points whichM.G.St. Hilaire wished to ascertain respect-ing the ornithorynchus. " There is neitherat the Linnæan Society, nor anyotlier institu-tion in London the egg’s of an ornithorynchus.One preparation has been seen and declaredto contain an egg ; Sir Everard Home ex-amined it, and declared that it was a mis-take. Sir E. H. states, that no one hastaken more pains to remove any doubts on theornithorynchi; he hopes ultimately to suc-ceed, the secretary of the Colonial depart-ment having taken some interest in thesubject."

The question whether the ornithorynchusbe viviparous or oviparous, has been stronglydiscussed. Geoffroy St. Hilaire and Cuviercontended for the latter point; Blainvilleand Home for the former. This matter,

however, has been satisfactorily settled bythe dissection of the animal recently made

by Meckel. He has demonstrated the exist-ence of mammary glands, and what has an

ovipancacs animal to do with such structures ?it no more lays eggs than a cow. The storyof M. Gregori is a fable.

PHYSIOLOGICAL OBSERVATIONS.

By JAMES CARSON, M.D. Liverpool.

(Continued from page 142.)Drt. BOSTOCK in the first volume of his

Physiology, published more than two yearsago, admits that I had established the doc-trine that the blood was returned to theheart in the veins by atmospherical pr6s-sure, and not as was previously supposedby the projectile force of the heart and ar-

teries. The Doctor, however, in allusion tothe causes by which atmospherical pressureis made to influence the motion of the bloodin the veins, says that some of the causesadduced by Dr. Carson are doubtful, andothers decidedly erroneous: among theformer he ranks the automatic expansionof the heart, in consequence simply ofthe relaxation of its fibres ; and amongthe latter, those decidedly erroneous, theelasticity of the lungs, but reserves his rea-sons for these opinions, prudently perhaps,to a subsequent part of his work. I shouldhowever have deened it a fairer method of

proceeding if the Doctor had withheld thestatement of his objections until he foundit convenient to support them by argument,rather’ than suspend over my head in ashapeless and intangible form for so long aperiod his threatened refutation, not withoutbiassing, for that time, the public opinion bythe weight of his authority. But my longsuspense has been abundantly atoned for, bythe actual though protracted birth of hisconceptions. The Doctor, in a note, for myname is not once mentioned in the body ofthe second volume, observes, in reference tothe resilience of the lungs, as follows : " Iconceive that the reasoning of Dr. Carsonon this subject is not well founded. His ex-periments made with a view to ascertain theelasticity of the lungs, he candiclly confessesto be imperfect in execution; nor do Ithink that the mode he employed will befound competent to the end in view. Phi.Trans. for 1820. p. 20, et seq. When the

lungs collapse they discharge a portion ofair; this will pass into the globe which lieemployed, and expel a part of the water intothe connected tube. But before we can ob-tain a measure in this way of the elasticforce of the lungs, we must ascertain theproportion that their bulk bears to that ofthe globe, and this, to the quantity of airexpelled from the lungs. Dr. ElHotson has,inadvertently, attributed the collapse whenthe thorax is opened, to the same causewhich produces ordinary respiration." The

compliment for candour which the Doctoris pleased to bestow upon me, I, perhaps