My former letter on this subject was merely to show that, mechanically, Dr. Pettigrew's view of the forward motion or inclination of a bird's wing during the down stroke was less absurd than had been supposed, and even seemed necessary to flight. I did not profess to have made accurate observation or experiment on the point. I accept, therefore, the observation of the Duke of Argyll as to the vertical motion of the heron's wing; but as he expressly refers to its great concavity, that would give a vertical down stroke the effect of a somewhat forward stroke of a flatter wing. The proper inference would therefore seem to be, that in birds with less concave wings the stroke is slightly directed forwards. As to the last two paragraphs of his Grace's letter, he will see, if he refers again to mine, that he has quoted words I never used. I impute to Dr. Pettigrew the "merit of showing" that the "slight upward angle of the mean position of the wing plane is essential to secure horizontal forward motion as a general resultant," &c., and this is exactly what the Duke denies.

Mr. James Ward's elaborate analysis of the down stroke of a bird's wing simply shows (if correct) that in the position he ascribes to it (moving downward and backward) it would send the bird horizontally forward. Of course it would. But then what becomes of the bird during the up stroke in an opposite direction? The bird is then falling, and by the downward reaction of all the solid surface of the anterior margin of the wing, and of all the feathers, however obliquely turned, it is driven farther

Lord Lindsay's Expedition

ALFRED R. WALLACE

The Newfoundland Cuttle Fish (Megaloteuthis harveyi S. Kent) My right being questioned, through an anonymous paragraph in the Globe of the 11th inst., to institute a new generic title for the gigantic Cephalopod encountered off Newfoundland, and of which I communicated an account to the Zoological Society's meeting of March 3, I would briefly reply to my criticiser in these columns.

In the first place, it is a somewhat anomalous proceeding to raise objections on such a question before details of the grounds upon which it has been deemed advisable to establish such a title have appeared, as in the ordinary course of events they will, in the Proceedings" of the Society. In these it will be found that ample reasons are given for the course that has been taken, as also due notice of both Prof. Steenstrup's and Prof. Verrill's researches in a similar direction. Had my assailant placed himself more thoroughly au courant with the details of the case, he would possibly have held back his emphatic assertion that Prof. Verril had "actually identified the species from Newfoundland with those described by Steenstrup as belonging to his genus Architeuthis." This identification in Prof. Verrill's own language is entirely problematical, and must unfortunately remain so, since a beak only, an organ of no value in generic discrimination, has been preserved of the typical species A. dux. Respecting the second form, A. monachus, we have still less knowledge, the title being provisionally instituted by Prof. Steenstrup for the reception of two gigantic Cephalopods cast on the shores of Jut-, land in the years 1639 and 1790, and of which popular record

alone remains.

In reference to the "imperfect evidence" asserted by my critic

QUETELET

February 17 last Jacques-Adolphe-Lambert Quetelet died at Brussels, in the seventy-eighth year of his age, having been born on February 22, 1796, at Ghent. At the early age of 18 he was appointed Professor of Mathematics in the College of his native town. In July, 1819, the degree of Doctor of Science was conferred on him by the University of Ghent, then recently founded by King William. His dissertation on this occasion was so well received that he was shortly thereafter appointed to the Chair of Mathematics at the Royal Athenæum of Brussels; and in February following was elected a member of the Academy of Sciences and Belles-Lettres.

At this time he applied himself with ardour to the cultivation of literature and pure mathematics, thus laying a sure foundation for the world-wide fame he afterwards achieved as an exact investigator in many departments of physics, as an original thinker in applying methods of scientific treatment to the discussion of problems pre. viously considered as belonging exclusively to moralists and divines, and as a clear and eloquent expounder of the truths he had demonstrated. The many-sidedness and fertility of his mind may be seen from his scientific memoirs enumerated in the Royal Society's Catalogue of Scientific papers, amounting at the close of 1863 to 220. He continued to write almost to the last, notwithstanding the mental malady, consisting in loss of memory, with which he was afflicted many years before his death, and it is noteworthy that even to the last his handwriting retained much of the rare grace and elegance for which it had been so remarkable.

The earliest of Quetelet's published memoirs, begun in 1820, were on geometrical subjects. The non-appreciation of these by the public determined him to devote himself to physical science and astronomy. On these subjects he lectured publicly with great success.

In 1823 he was sent on a mission to Paris with the view of preparing a report on the observatory of that city for the guidance of the Belgian Government in founding a similar observatory at Brussels. After some delay, the observatory was established, with Quetelet as director, and in 1833 began the long series of observations on astronomy, meteorology, and other physical inquiries, for which this observatory is so well known. The most important of his astronomical observations was the prepara

tion of a catalogue, begun in 1857, of stars which seem to have appreciable motion. He also began, so early as 1836, systematically to observe and record the occurrence of meteors and shooting-stars. These observations came to be of great value thirty years later, when the true nature of these bodies was satisfactorily established. The meteorological observations at this observatory have been particularly full and valuable, embracing hourly and bi-hourly observations, published annually in extenso, of atmospheric pressure, temperature, humidity, rain, cloud, &c. These have been exhaustively discussed by Quetelet in "La météorologie de la Belgique comparée à celle du globe," published in 1867. In this admirable treatise we have what must still be regarded as the fullest and best account of the meteorology of any single locality on the globe-the yearly, monthly, daily, and hourly march of the various meteorological elements being given. In the same volume are given résumés of the observations made at the other stations which began to be established at Alost, Ghent, Liége, &c., in 1835.

He was elected perpetual secretary of the Academy of Sciences and Belles-Lettres in November 1834, and was chiefly instrumental in adding a section on the Fine Arts in 1845 It is scarcely necessary to refer to the scientific contributions he made to the Fine Arts, by his extensive and minute investigations regarding the proportions of the human body, the results of which are given in his “Anthropométrie." In matters relating to the higher education, to the census, and other national questions, the Belgian Government wisely availed itself repeatedly of his wide knowledge and great experience.

His first paper on the subject of statistics was published in 1826; in 1835 appeared his "Physique sociale," and ten years later his " Lettres sur la théorie des probabilités appliquées aux sciences morales et politiques." In 1841 a Central Commission of Statistics was established by royal decree, of which Quetelet was made president, and of which he continued to be president to his death. He originated the idea of convening an International Congress of Statistics. The first was held in Brussels in 1853, and others have since been held at Paris, London, Berlin, Florence, the Hague, and St Petersburg. It is in the field of statistics that Quetelet appears as a great discoverer, and his success in this department must be attributed to the clearness with which he saw that statistics occupy the ground in the development of the social and political sciences which observational data do in the development of such sciences as astronomy and meteorology, to the patient industry with which through long years he gathered together his facts, and to the mathematical skill he brought to bear on the discussion of the results. He was truly, as expressed by the Academy of Berlin in their congratulatory letter on the occasion of the centenary of the Belgian Academy, "the founder of a new science which proceeds from the firm basis of observation and calculation to discover and unfold those immutable laws which govern the phenomena, apparently the most accidental, of the life of man, down even to his most trivial actions."

WE E have received advanced sheets of the Report of

the Secretary of the United States Navy, of the examination of those of the crew of the Polaris who were in the ship when she broke loose from the floe to which she was anchored, on October 15, 1872, leaving the nineteen persons on the sheet of ice which was their floating home, until picked up about six months after off the coast of Labrador (NATURE, vol. viii., p. 217). This report confirms the opinion we have already expressed that no Arctic expedition can be adequately conducted unless carried out under naval discipline. It was only

on account of the good intentions and good nature o the crew, especially after their noble and enthusia captain's death, that things went on as smoothly a they did. Captain Buddington seems to have had heart in the object of the expedition, and we cam help thinking that had he not been with it much me would have been gained. It was in deference to b opinion that Captain Hall refrained from trying to pus beyond his furthest point (82° 16' N.) with the ship: a the other officers, though they do not seem to have bet. very well assorted, being of opinion that an attempt should be made to get further north, or at least not to lose ground by wintering further south.

We have already (vol. viii., p. 435) given details as to the rescue of those who were left in the Polaris, and of their being landed in Scotland by the Arctic and Eric whalers The present report affords some idea of the scientific results of the expedition, a detailed account of which will no doubt by and by be published, although we regret to su that many of the records of the scientific results were lost in the confusion incident to the parting of the ship from the floe. Still much that is valuable has been brought home, from which many additions to a scientific knowledge of that part of the Arctic region will be obtained. Notwithstanding the want of perfect harmony among the officers, the scientific work of the expedition seems to have been diligently carried on, and the evidence of Dr. Bessels especially contains a great deal of value to Science. Geographers will be able to correct and extend their maps of the regions visited, and we hope that very soon the complete material for enabling them to do so will be in their hands. Constant and careful tidal observations were carried on, with the very valuable result of ascertaining that the tide of Thank-God Harbour, 81° 38' N. is produced by the Atlantic but by the Pacific tidal wa It was found," Dr. Bessels says, "that the co-tidal hour is about 16h 20m. Rensselaer Harbour, being the norther most station, has its co-tidal hour at 18h 04, consequent the tide comes from the north, the rise and fall at spring. tides amounting to about 5 ft.; at neap tides 2,5. Most likely the two tidal waves meet somewhere in Smith Sound, near Cape Frazier. Kane and Hayes have bott found a ridge of hummocks near Cape Frazier, and in drifting down we experienced that during some time, being abreast of Cape Frazier; we hardly made any headway. but we drifted both north and south."

The results of the expedition may be summed briefly as follows :-(1) the Polaris reached 82° 16′ N, a higher latitude than has been attained by any other ship; (2) the navigability of Kennedy Channel has been proved beyond a doubt; (3) upwards of 700 miles of coast-line have been discovered and surveyed; (4) the insularity of Greenland has been proven; and (5) merous observations have been made relating to astronomy, magnetism, force of gravity, ocean physics, meteorology, zoology, ethnology, botany, and geology, the records of which were kept in accordance with the instructions supplied by the National Academy, and some of the results of which we propose briefly to enumerate.

ASTRONOMY.--Great care was taken in determining a reliable meridian at Thank-God Harbour. Soon after entering winter-quarters an observatory was erected on the shore, thirty-four feet above mean sea-level, and the transit instrument stationed there. The longitude of this station was determined by the observation of 300 lunar distances; a number of moon culminations; a great number of star transits; a number of star occultations; a great number of altitudes of the sun on or near the prime vertical. Its latitude, by the observation of a great number of circummeridian altitudes of the sun, and a number of altitudes of stars. All of these observations were lost, but a number of the results have been pre served which are sufficient to establish the position of his station.

The instruments used in the above observations were a Würdemann transit and Gambey sextants divided to 10". The expedition carried six box chronometers made by Negus, three of which indicated sidereal time, and four pocket chronometers by different English makers. These time-pieces were compared every day at precisely the same time, and the result entered in the chronometerjournal.

Besides the above-mentioned observations, twenty sets of pendulum experiments were made, which are saved, but the observations for time belonging to them are lost. MAGNETISM. The magnetic observations obtained were more complete than any others ever before made in the Arctic regions. The instruments supplied were: -one unifilar declinometer; one dip circle, with Lloyd's needles; one theodolite; and several prismatic compasses.

The observations on variation of declination were registered at Göttingen time, and were continued for five months readings taken hourly. Besides that, three term days were observed every month, according to the Göttingen regulations, one of these term days corresponding with the day accepted by all the magnetic stations. Further, a number of observations were taken either with the theodolite or the prismatic compass. Whenever possible, the dip was observed, and several sets of observations on relative and absolute intensity and of the moment of inertia were obtained.

OCEAN PHYSICS —Unfortunately there was not much opportunity for taking soundings. About twelve were obtained along the coast of Grinnell Land, which prove that the hundred-fathom line follows the coast at a distance of about 15 miles in Smith's Sound. One of these soundings (90 fathoms) proved highly interesting, containing an organism of lower type than the Bathybius discovered by the English dredging expedition. It was named Protobathybius robesonii.

A number of deep-sea temperatures were taken with corresponding observations on the density of the water. Following the coast of West Greenland the limits of the Gulf Stream were ascertained. Specimens of water from different depths were preserved in bottles, but were, unfortunately, lost.

As soon as the vessel was fairly frozen in, a tide-gauge was erected over a square hole cut in the ice-floe, and kept open continually; the pulley and rope were supported by a tripod of oars. A rope, to which a wooden scale, divided into feet and inches, was fastened, was carried through a block attached to the tripod. One end of the rope was anchored at the bottom by means of two thirtytwo pound shot, and a counterpoise was attached to the other end to keep the rope properly stretched. This apparatus was tested by a series of scale readings with corresponding soundings, and proved to work very satisfactorily. The observations comprise eight lunations, the readings being taken hourly, half-hourly, and in some instances every ten minutes, in order to determine the precise moment of the turn of the tide.

METEOROLOGY.-After having entered winter-quarters meteorological observations, which up to this time had been made three-hourly, were made every hour, Washington time. The register contained observations on the temperature of the air, atmospheric pressure, psychrometrical observation, direction and force of wind, appearance of the sky, state of weather, and both solar and terrestrial radiation. Besides, all extraordinary meteorological phenomena were carefully noted.

For the registration of the temperature of the air mercurial thermometers were used for temperatures down to -35 F.; for lower ranges spirit instruments being compared at intervals of 10°. As circumstances would permit, mercurial or aneroid barometers were used. As it was not supposed that psychrometrical observations could be favourably conducted at very low temperatures, the expedition was not supplied with the suitable instru

ments. For that reason two uncoloured spirit thermometers were selected and used, the readings of which agreed. As check observations the dew-point was determined by means of Regnault's apparatus. To measure the velocity of the wind, Robinson's anemometer usually served. The distance travelled by the wind was noted hourly, at the same intervals of time. The velocity of the wind was determined either by the same instrument or by means of Casella's current-meter. These observations on the winds, combined with those on moisture of the atmosphere, will form a valuable contribution to physical geography.

It was not thought essential to procure photographs of the clouds, as they do not differ in their general character from those in more southerly latitudes. The only remarkable fact to be noticed is that sometimes cirri could be observed at very low altitudes among stratus clouds, which, however, is not surprising if their mode of formation is taken into account.

Special attention was devoted to the aurora borealis, which occurred frequently, but rarely showed brilliant colours, never bright enough to produce a spectrum. Whenever necessary one observer was stationed at the magnetometer and the other out-doors, the former observing the motions of the magnets, while the other was watching the changes in the phenomenon and taking sketches. Although an electroscope and electrometer were set up, and the electrical condition of the atmosphere frequently tested, in no instance could the least amount of electricity be detected. The amount of precipitation was measured as carefully as the violent gales would permit, by means of a rain-gauge supplied with a funnel. In February, as soon as the sun re-appeared, observations on solar radiation were commenced, and continued throughout the entire summer. The instruments employed were a common black-bulb thermometer, and one in vacuo; both exposed on white cotton.

ZOOLOGY AND BOTANY.-The collections of natural history are almost entirely lost. With the exception of two small cases containing animals, minerals, and one package of plants, nothing could be rescued. The character of the fauna is North American, as indicated by the occurrence of the lemming and the musk ox. Nine species of mammals were found, four of which are seals. The birds are represented by twenty-one species. The number of species of insects is about fifteen, viz.: one beetle, four butterflies, six diptera, one bumble-bee, and several ichneumons, parasites in caterpillars. Further, two species of spiders and several mites were found. The animals of lower grade are not ready yet for examination.

The flora is richer than could be expected, as not less than seventeen phanerogamic plants were collected, besides three mosses, three lichens, and five fresh-water algæ.

GEOLOGY. Although the formation of the Upper Silurian limestone, which seems to constitute the whole west coast north of Humboldt Glacier, is very uniform, some highly interesting and important observations have been made. It was found that the land is rising, as indicated, for instance, by the occurrence of marine animals in a freshwater lake more than 30 feet above the sea-level and far out of reach of the spring-tides. Wherever the locality was favourable the land is covered by drift, sometimes containing very characteristic lithological specimens, the identification of which with rocks in South Greenland was a very easily accomplished task. For instance, garnets of unusually large size were found in latitude 81° 30', having marked mineralogical characteristics by which the identity with some garnets from Fiskernaes was established. Drawing a conclusion from such observations it became evident that the main line of the drift, indicating the direction of its motion, runs from south to north.

THE COMMON FROG*

O

XII.

dition. Its larval, or tadpole stage, presents us with

a series of changes which, though more familiar, are not less wonderful.

In the first place, however, it may be well to describe shortly the condition of the circulation in fishes, where the purification of the blood is effected, not by means of the exposure of the blood to the action of air taken into respiratory cavities of the body, but by its subjection in little plates of membrane, the gills, to the influence of air mechanically mixed up with and dissolved in the water in which those gills are bathed.

In fishes, moreover, unlike all air-breathing animals, none of the oxygenated blood is returned to the heart for propulsion, but is collected directly into the great dorsal aorta, whence it is distributed to the whole body, only being returned to the heart after such distribution, so that venous blood alone enters that organ.

This venous blood is sent out from the heart through a bulbous aorta, whence arise on each side a series of arteries which ascend the branchial arches, one on the outer side of each such arch, decreasing in size as it ascends.

Each branchial artery gives off small gill arteries, which run along one edge of each little membranous leaflet or gill, and supply it with minute branches ending in capillaries, in which the blood is purified. There the purified blood is taken up by minute veins which open

into gill veins, one of which runs along the opposite edge

of each gill to that occupied by the gill artery.

The gill veins pour their contents into branchial veins, one of which ascends the outer side of each branchial arch, increasing in size as it ascends. The branchial veins open into the great dorsal aorta, whence the blood is distributed over the body. Generally the branchial arteries are only connected with the branchial veins by the intervention of the capillary vessels of the gills. Sometimes, however (as e.g. in the mud-fish, Lepidosiren), the branchial veins are directly continuous with the branchial

arteries.

In the tadpole, while the gills remain fully developed, a condition exists quite similar to that of fishes. Minute vessels, however, directly connect together, at the root of each gill, the branchial artery and branchial vein of each gill. Such a connecting vessel is termed a ductus botalli. A minute vessel given off from the third branchial artery, is the incipient pulmonary artery.

As development proceeds, as the gills diminish by absorption, and as their respective arteries and veins decrease in size and importance, each ductus botalli increases until at last we have established the six great continuous vessels of the adult frog.

We have, then, in the life-history of the frog, a complete transition from the condition of the fish to that of a true air-breathing vertebrate, as regards its circulation. The various conditions herein referred to have, however, an important bearing on the question of the first origin of such structure.

All higher animals, even the very highest, have the great arteries, when they first appear, arranged substantially as in fishes.

From the common aortic bulb five vessels ascend each side of the neck, and more or fewer of these arteries abound in different classes, the permanent adult condition being arrived at by this circuitous route.

This argument has commonly been adduced as an argument in favour of the descent of air-breathing animals from more ancient gill-bearing forms, and it is not without weight.

* Continued from p. 369

FIG. 78.-Infero-lateral view of Head and Aortic Arches of Lepidosiren (after Hyrtl). a, esophagus; b, anterior end of bulbus aorta, common roots of the first aortic arches; d, third aortic arch, e, first aortic arch. f, dorsal union of the first three aortic arches; g, aorta: &, celiac artery: i, exit of the fifth nerve; k, part of operculum; 4, ent of the nervus vagus from the skull; m, branches to esophagus;, nerve going to the rectus abdominis; o, nervus lateralis;, first and hypertrophied nb: 7, posterior part of the skull: r. segmented neural spines; s, chorda dor salis; t, mandible; %, quadrate.

becomes broken up into an artery and a vein connected by a net-work of capillaries.

Now we can understand the series of unbroken arches in higher animals as the relics of ancestral vessels which divided for gill circulation and were therefore once of etreme functional importance and utility. But how can we understand the primitive unbroken series of arches in Fishes? Their utility was yet to come!

The frog when adult has, besides its skin, no breathing organs but the lungs. As has been said before, other members of the Frog's class retain gills and aquatic respiration during the whole of life, as for example Menobranchus.

Every one kind, however, whether provided perma nently with gills or not, develops lungs, and it might easily be imagined that similarly every gilled-creature which has lungs is also a Batrachian.

FIG. 79.-The Circulation of a Tadpole in its primitive stage, when nearly all the blood is distributed to the gills; the pulmonary arteries bet quite rudimentary, and the vessel (or ductus botalli) connecting toge ther the branchial artery and vein at the root of each gill being minute a, bulbus aortæ; b, branchial arteries; bri, bra, br3, the three gills branchia of each side); b, the branchial veins which bring back the blood from the gills-the hindermost pair of branchial veins on each side unite to form an aortic arch (aa), which again unites with its fellow the opposite side to form da, the descending (or dorsal) aorta. The branchial veins of the foremost gills give rise to the carotid arteries, o, artery going to the orbit; pa, pulmonary artery; 1, 2, 3, anastomosin branches connecting together the adjacent branchial arteries and veins

This, however, would be a mistake.

than once, is furnished with both gills and lungs through The Mud-fish or Lepidosiren, already referred to more out the whole of life. On this account it has been reckoned by some naturalists to be a Fish and not a Batrachian. Its fish-nature, however, has now been tho