ON THE ECLIPSE EXPEDITION, 1871* I UNDERSTAND my duty to-night to be to give an account

of the observations made, not by all who observed the eclipse of last December, but by the members of the party which went out under the auspices of the British Association; and it is extremely fortunate that nothing more is required of me-first, because most valuable work was done by the other parties, which of itself would require more time to state than I have at my disposal; and secondly, because the amount of material obtained by the members who were sent out from England, and by the friends who met them at every point, is so great, that it would be impossible in one discourse to give anything like an exhaustive account of it. Here are some of the records in this portfolio. You will see at once that even for one party I can only make a selection, and I am perfectly aware of the extreme responsibility which attaches to anyone who may venture to make a selection out of such an enormous mass of material as we have collected.

Before I proceed to discuss the work done by the different parties, it will be desirable to give an idea of the arrangements, and for this purpose I have prepared several maps which will enable you to see what the British Association parties did.

In the first instance I may remark that the weather conditions were somewhat problematical. Another point of great importance was that much of the ground was fortunately occupied, and it was essential, when placing the parties, to bear these two considerations in mind-the possibility of bad weather, and then the importance of so arranging matters that if some of the observers were clouded out, belonging to our parties, then the story might be continued by other observers.

Here we have a map of India, which gives you a general idea of the path of the shadow during the eclipse. The shadow, you see, strikes India on the western coast, and it runs down in a south-westerly direction, and cuts the northern portion of Ceylon. When we arrived in India we found that the Indian observers, consisting of those well-known men Tennant, Herschel, Hennessy, Pogson, and others, had determined, from their knowledge of the climatic conditions of India at that time of the year, to occupy the central part of the line, and also a station at a low level; the eminent French physicist M. Janssen taking up his We were to station ourposition at the top of the Nielgherries. selves either east or west, or both, of these parties. Whether east or west would depend upon the monsoon, and the great question that was being discussed on our arrival was, Was the monsoon favourable?

I have not time to go into the many interesting points touching the answer to this question; but I may say shortly that what we heard was, that if the weather was likely to be bad on the east side of the hill range, generically called the Ghauts, there was a good chance for anyone occupying a position west of those hills. What happened was that we did occupy the positions marked by blue wafers on the map, namely, Bekul on the west coast, Manantoddy on the western slope of the Ghauts, Poodocottah in the eastern plain, and in the island of Ceylon, first, Jaffna, and secondly, Trincomalee.

Such were our arrangements. The parties were stationed along the line of totality. Very different were the arrangements of the Sicilian party of the former year. In Sicily we were compelled to throw ourselves across the line of totality in the direction which I have indicated on this map of Sicily.

Now what was the work we had to do? If you will allow me to refer to two or three results of the former Eclipse Expedition, I will endeavour to put them before you without taking up too much of your time.

One of the most important among the results obtained in the eclipse of 1870 was this: far above the hydrogen which we can see every day without an eclipse-far above the prominences, the spectrum of hydrogen had without doubt been observed by two or three of the American observers, who were more fortunate than we were. Among them Prof. Young stated that the spectrum of hydrogen was observed to a distance of 8 minutes from the sun; he then adds, "far above any possible hydrogen atmosphere.' This is point number one.

Another of the points was this: the unknown substance which gives us a line coincident, according to Young, with a line numbered 1474 by Kirchhoff, had been observed by the American

A Lecture delivered at the Royal Institution of Great Britain, Monday, March 22, 1872, by J. Norman Lockyer, F.R.S. (The chief results obtained by the expedition have been taken from the ad interim Report presented to the British Association Meeting at Brighton. The lecture itself dealt mainly with the methods and instruments employed.-J. N. L.)

observers to a height of 20 minutes above the limb of the dark

moon.

Now, it was a very obvious consideration that if we got a spectrum of hydrogen 8 minutes from the dark moon, when we thought we knew that the hydrogen at the sun did not really extend more than 10 seconds beyond the dark moon, there was something at work which had the effect of making it appear very much more extensive than it really was; and it was fair to assume that if this happened in the case of the hydrogen, it might also happen in the case of the unknown stuff which gives us the line 1474.

In support of this view we had one of the few observations which were made in Sicily, in the shape of a drawing of the corona, as seen by Prof. Watson, who observed at Carlentini. He saw the corona magnificently; and being furnished with a powerful telescope, he made a most elaborate drawing of it, a rough copy of which I will throw on the screen. You will see at once that we had in this drawing something which seemed to militate against the idea that the 1474 stuff at the sun did exist to a height of 20 minutes. According to Prof. Watson the boundary of the real corona was clearly defined, its height being far under that stated.

Next, we had another observation of most important bearing on our knowledge of the base of the corona. I refer to the announcement of the observation by Prof. Young of a stratum in which all the Fraunhofer lines were reversed. It was asserted that there was undoubtedly a region some 2 seconds high all round the sun, which reversed for us all the lines which are visible in the solar spectrum. We had, in fact, in a region close to the photosphere the atmosphere of the sun demanded by Kirchhoff at some distance above the photosphere.

Last, not least, we had the photographic evidence. There was in Sicily a photographic station in Syracuse, and the Americans had another in Spain. I now show on the screen a drawing-it is not the photograph itself-but a drawing of a photograph made by the party in Sicily; what we have on this photograph is a bright region round the dark moon, which is, undoubtedly, solar, but stretching out right away from this, here and there are large masses of faint light, with dark spaces between them, which have been called rifts. Now the question is, Is this outer portion solar?

Having thus brought rapidly before you some of the questions which we had principally to bear in mind, and, if possible, settle (though that is too much to hope for in any one Eclipse Expedition) in the work we had to do in India, I will next bring to your notice some new methods of inquiry which had been proposed, with the object of extending former observations.

I may here remark that the Royal Astronomical Society, in the first instance, invited me to take charge of an expedition to India merely to conduct spectro-copic observations; but although this request did me infinite honour, I declined it, because the spectroscope alone, as it had been used before, was, in my opinion, not competent to deal with all the questions then under discussion. I have told you that some of the most eminent American observers had come to the conclusion that the spectrum of hydrogen observed in the last eclipse round the sun, to a height of 8 minutes, was a spectrum of hydrogen "far above any possible hydrogen at the sun. Hence it was

in some way reflected. Now with our ordinary spectroscopic methods it was extremely difficult, and one might say impossible, to determine whether the light which the spectroscope analysed was really reflected or not; and that was the whole question.

It became necessary, therefore, in order to give any approach to hopefulness, to proceed in a somewhat different way in the 1871 expedition; and, in order to guard against failure, to sup. plement such new observations by photographs; and fortunately we were not long in coming to a conclusion that this might be done with some considerable chance of success.

I have here a train of prisms. I will for one moment take one prism out of the train, and we will consider what will happen if we illuminate the slit of the lantern with a monochromatic light, and observe it through the prism. If we render sodium vapour incandescent, we know we get a bright yellow image of the slit, due to the vapour of the metallic sodium only giving us yellow light. But why is it that we get a line? Because we always employ a line for the slit. But suppose we vary the inquiry? If, instead of a straight line we have a crooked line for the slit, then we ought to see a crooked line through the prism.

Now, allow me to go one step further: suppose that instead of a line, whether straight or crooked, we have a slit in the shape of a ring, shall we see a ring through the prism? You will see that we shall. And then comes this question: If, when we work in the laboratory we examine these various slits, illuminated by these various vapours, why should it not happen that if we observe the corona in the same way, we shall also get a ring built up by each ray of light which the corona gives to us; since we know, from the American observations, that there were bright lines in the spectrum of the corona, as observed by a line slit? In other words, the corona, examined by means of a long❘ train of prisms, should give us an image of itself painted by each ray which the corona is competent to radiate towards us.

Now let us pass to the screen, the screen merely replacing the retina. We will first begin with the straight slit with which you are familiar-we now have our slit fairly focussed on the screen-we then in the path of the beam interpose one of these prisms, and there we get on the screen a bright line.

Now, to continue the argument, we replace the straight slit by a crooked one, and you see we get a crooked image on the screen. We now replace this crooked slit by a ring. We have now a ring-formed image on the screen. So that you see we can use any kind of narrow aperture we choose, and as long as we are dealing with light which is monochromatic, or nearly so, we get an image of the aperture on the screen.

If we consider the matter further, it will be evident that we may employ a mixture of vapours, and extend this result.

We will now, for instance, instead of employing sodium vapour, employ a mixture of various vapours. You see now that each ray given by these substances, instead of building up a line image, is building up for us a ring image-that we have now red, green, yellow, blue, and violet rings.

Now that was the consideration which led to the adoption of one of the new attempts to investigate the nature of the corena used this time. It was, to use a train of prisms, pure and simple, using the corona as the slit, a large number of prisms being necessary to separate the various rings we hoped to see, by reason of their strong dispersion. On the screen the rings to a certain extent intersect each other; and it would have been easier to show you the ring-form of the images if we could have used more prisms than one.

If this is good for a train of prisms such as I have referred to, it is good for a single prism in front of the object-glass of a telescope. Such was the method adopted by Prof. Respighi, the distinguished Director of the Observatory of the Capitol of Rome, who accompanied the expedition.

Now you may ask how would this method, if it succeeded, be superior to the ordinary one? In this way. If we were dealing merely with reflection, then all the rings formed by vapours of equal brilliancy at the base of the chromosphere would be of the same height, while if reflection were not at work, the rings would vary according to the actual height of the vapours in the sun's atmosphere, and the question would be still further advanced if the spectrum did not contain a ring representing the substance which underlies the hydrogen.

Our new spectroscopic equipment then was as follows:-
I. A train of five prisms.

2. A large prism of small angle placed before the object-glass of a telescope.

3. Integrating spectroscopes driven by clockwork.

4. A self-registering integrating spectroscope, furnished with telescopes and collimators of large aperture, and large prisms. (This instrument was lent by Lord Lindsay.)

Now a word about the polariscopic instruments, referring you to my lecture given last year for a general notion of the basis of this class of observation.

A new idea was that observations to determine the polarisation of the corona might be made with the same telescope and eye, both with the Biquartz and the Savart.

By the kindness of Mr. Spottiswoode, who has placed his magnificent polarising apparatus at our service, I hope to be able to show you on the screen the mode of examining the corona by means of those two instruments, so as to enable you pretty well to follow what was actually done.

Let me begin with the Biquartz polariscope. In the first instance I will throw on the screen a representation of the corona itself, and we will then insert a Biquartz, and see its effect when I flood the screen with polarised light. You now see an indication of what would be observed supposing the polarisation was due to polarised light diffused in the region between us and the dark moon and eclipsed sun, in which case the

polariscopic effect would be observed generally over the dark moon, the corona and the region of the sky outside the corona. But this is not all; not only does this arrangement enable us to determine the existence of such a general polarisation, but the vertical line in the Biquartz called the line of junction indicates the plane of polarisation, when the colours on both sides of it are the same; so that we have two colours strongly contrasted in either half of the field when we are away from the plane of polarisation, and a uniform colouring of the whole field when in or at right angles to that plane. By turning this prism through 90 degrees, you see I entirely change the colours.

But we are not limited to the Biquartz in this inquiry. We can apply the Savart polariscope. Having still our image of the corona on the screen, I now replace the Biquartz by a Savart.

We now no longer see a line of junction with the similar or different colours on either side of it, but lines of colour running across the image. I turn the prism. We first see the lines with a white centre, then with a dark one; while at times they are altogether absent. And as a departure from the plane, when we use the Biquartz, gives us the strongest contrasts of colour, so you observe that with the Savart under these circumstances all indications of polarisation vanish.

Now, if we assume polarisation to be general, and the plane of polarisation vertical, we should get those coloured bands, as you see them there, crossing the corona and dark moon, the lines being vertical and dark-centred. If the plane of polarisation were horizontal, we should find the lines horizontal and the central one white.

But so far as we have gone, we have been dealing with polarisation which is general, and we have not attempted to localise polarisation at the corona itself. But I have here an apparatus,

by means of which, quietly, in this theatre one can see as admirable an example as we should desire of polarisation, assumed to be particular to the sun and not general-I mean radial polarisation. We have simply a circular piece of mahogany, or something else which polarises light equally well, with a hole in the middle with sloping sides, cut as you see this cut, and then we place behind it a candle, so that the light of this candle, after falling on oiled tissue paper stretched across the aperture, can be reflected to the eye by the sides, the direct light of the candle being stopped by a central metallic diaphragm. We have now a source of polarised light of a different kind from the last. The next thing we have to do is to introduce into a small telescope exactly the same kind of apparatus we have there, though of course on a much smaller scale, and examine the ring of light seen when we put the candle behind the aperture. On examining the ring of light which is now visible by means of this telescope, which contains a Biquartz and analyser, I see the most exquisite gradations of colour on either side the line of junction which cuts the field of view and the bright ring in the centre into two.

Now, instead of the candle, we will employ the electric lamp; and instead of the eye, the screen; but I must inform you that the great heat of the electric lamp prevents the appearance being perfectly successful on the screen, as the reflecting varnish is

melted.

In this experiment we cannot work with an image of the corona. We must make our corona out of the image of the ring we hope to get on the screen; and then, by employing the Biquartz in the same way as before, instead of getting similar colours on either side of the line of junction, as we did when we were working in the plane of polarisation, and getting the greatest contrasts, as we did when we worked 45 degrees away, you observe we get different colours in each part of the ring.

On the screen we now have a highly-magnified image of the hollow cone of iron which I am compelling to reflect the light from the lamp; and by inserting this Biquartz I throw various colours over different portions of that ring, which I beg you to consider for one moment as the solar corona, and the colours change as I rotate this prism. You will at once be able to explain the different actions of this Biquartz in this instance. The reflection, and therefore the plane, of polarisation is no longer general, but varies from point to point of the reflecting surface. It is in fact radial, and hence the delicate radiate arrangement of colour.

Such, then, were some of the new methods and new instruments we used for the first time in our researches. And I hope you will allow me to use this term, although our work was conducted a long way from the Royal Institution, the natural home of research in England.

(To be continued.)

SOCIETIES AND ACADEMIES

LONDON

Geological Society, Nov. 6.-Prof. Ramsay, F.R.S., V.P., in the chair. A Report by F. T. Gregory, Mining Land Commissioner in Queensland, on the recent discoveries of Tinore in that Colony. According to this report, the district in Queensland in which tin-ore has been discovered is situated about the head-waters of the Severn river and its tributaries, comprising an area of about 550 square miles. The district is described as an elevated granitic table-land intersected by ranges of abrupt hills, some attaining an elevation of about 3,000 feet above the sea. The richest deposits are found in the beds of the streams and in alluvial flats on their banks, the payable ground varying from a few yards to five chains in extent. The aggregate length of these alluvial bands is estimated at about 170 miles, the average yield per linear chain of the stream-beds at about ten tons of ore (cassiterite). Numerous small stanniferous lodes have been discovered, but only two of much importance, namely, one near Ballandean Head Station on the Severn; and another in a reef of red granite rising in the midst of metamorphic slates and sandstones at a distance of about six miles. The lodes run in parallel lines bearing about N. 50° E.; and one of them can be traced for a distance of nine or ten miles. The ore, according to Mr. Gregory and Mr. D'Oyly Aplin, is always associated with red granite, ie. "the felspar a pink or red orthoclase, and the mica generally black; but when crystals of tin-ore are found in situ, the mica is white." The crystals of tin-ore are generally found in and along the margins of quartz threads or veins in bands of loosely aggregated granitoid rock, but are sometimes imbedded in the micaceous portions. The report concludes with some statements as to the present condition and prospects of the district as regards its population.-Observations on some of the recent Tin-ore discoveries in New England, New South Wales, by G. H. F. Ulrich. The district referred to by the author is in the most northern part of the colony of New South Wales, almost immediately adjoining the tin-region of Queensland described in the preceding report. It forms a hilly elevated plateau, having Ben Lomond for its highest point, nearly 4,000 feet above the sea-level. The predominant rocks are granite and basalt, enclosing subordinate areas composed of metamorphic slates and sandstones; the basalt has generally broken through the highest crests and points of the ranges, and spread in extensive streams over the country at the foot. The workings of the Elsmore Company, situated on the north-west side of the Macintyre river, about twelve miles E. of the township of Inverell, include a granite range of about 250 feet in height, and nearly two miles in length. The granite of the range is micaceous, with crystals of white orthoclase, and is traversed by quartz veins which contain cassiterite in fine druses, seams, and scattered crystals, and by dykes of a softer granite, consisting chiefly of mica, and with scarcely any quartz, in which cassiterite is distributed in crystals, nests, and bunches, and also in irregular veins of several inches in thickness. This granite yields lumps of pure ore up to at least 50 lbs. in weight. The quartz veins contain micaceous portions which resemble the "Greisen" of the Saxon tin mines. The deepest shaft sunk in one of the quartz veins was about 60 feet in depth. The author noticed certain minerals found in association with the tin ore, and the peculiarities of the crystalline forms presented by the latter. In conclusion the author referred to the probability that a deficiency of water may prove a great obstacle to the full development of the tin-making industry in this district, but stated that "it seems not unlikely that the production of tin ore from this part of Australia will reach, if not surpass, that of all the old tin-mining countries combined."-"On the included Rockfragments of the Cambridge Upper Greensand." By W. Johnson Sollas and A. J. Jukes-Browne. The occurrence of numerous subangular fragments in the Upper Greensand formation was so far remarkable that it had already attracted the notice of two previous observers (Mr. Bonney and Mr. Seeley), who had both briefly hinted at the agency of ice. While ignorant of the suggestions of these gentlemen, the authors of this paper had been forced to the same conclusion. A descriptive list had been prepared of the most remarkable of the included fragments. The infallible signs of the Upper Greensand origin consisted in incrustations of Plicatula sigillum, Ostrea vesiculosa, and "Coprolie," without which, it was stated, the boulders would be undi tinhable from those of the overlying drift. The following genens were then put forward:-1. The stones are mostly

ra

3. The

subangular; some consist of friable sandstones and shales, which could not have borne even a brief journey over the ocean bed. 2. Many are of large size, especially when compared with the fine silt in which they were imbedded; the stones and silt could not have been borne along by the same marine current. stones are of various lithological characters, and might be referred to granitic, schistose, volcanic, and sedimentary rocks, probably of Silurian, Old Red Sandstones, and Carboniferous age. Such strata are not found in situ in the neighbourhood, and the blocks must have come from Scotland or Wales. Numerous arguments were adduced in favour of their Scottish derivation. The above considerations, that numerous rock fragments, some of which are very friable, have been brought from various localievidence for their transportation by ice; the majority showed ities and yet retain their angularity, were thought sufficient no ice scratches, but the small proportion of scratched stones in the moraine matter borne away on an iceberg, and the small percentage of ice-scratched boulders in many deposits of glacial drift, show that the absence of these striæ is not inconsistent with the glacial origin of the included fragments. Besides this the stones of the Greensand consisted of rock, from which ice marks would readily have been removed by the action of water. The authors stated, however, that they had found more positive evidence in a stone which was unmistakably ice-scratched, consisting of a siliceous limestone, and preserved in the Woodwardian Museum. The fauna, so far as it proved anything, suggested a cold climate; though abundant, the species were dwarfed, in striking contrast to those of the Greensand of Southern England and the fauna of the succeeding Chalk.

The authors concluded

that a tongue of land separated the Upper Greensand sea into two basins, the northern of which received icebergs from the Scottish-Scandinavian chain; the climate of this was cold, that of the southern basin much warmer.

PARIS

Academy of Sciences, Nov. 4.-M. Faye, President.— The first paper read was by M. Becquerel, on the solar origin of atmospheric electricity. A large portion of the paper was preliminary, and contains a sketch of modern solar discoveries; the subject is to be continued.-M. Pasteur then read a note on the production of alcohol by fruits. His remarks referred to some experiments by M. Lechartier, who has found that alcohol is developed in fruit on simple keeping.-Another note by the same author followed, replying to some of M. Fremy's late assertions. To this M. Fremy replied, and was immediately answered by M. Pasteur, who demanded the appointment of a commission to examine his experiments, when M. Fremy arose and proposed that he, M. Pasteur, and M. Trécul should work in common. M. Dumas then stated that the Academy should grant the request of M. Pasteur. M. Wurtz supported M. Pasteur's demand, and M. Pasteur then asserted that he would not agree to M. Fremy's proposed joint work, and urged the appointment of a commission to examine the contested experimental evidence. After this the discussion dropped. -Another of MM. Favre and Valson's papers on crystalline dissociation was then read. The authors described a new method for the investigation of the " COercive action of a salt on water at any temperature.-M. Faye then read a paper on Mr. L. Rutherfurd's lunar photographs. -Next came a report on a memoir by Dr. Dufossé on the noises and sounds which the sea and freshwater fish of Europe can hear. The report recommended that the thanks of the Academy should be awarded to the Doctor for his discoveries. M. Max Marie then presented a paper on the elementary theory of Integrals of any order, and of their periods. Becquerel then presented an addendum to M. E. Jannettaz's late note on the coloured rings of gypsum. The note by M. Jannettaz contained some additions to and corrections of his former communication.-M. D. Colladon then presented a note on the effects of lightning on trees, which was referred to the Lightning Conductor Commission. MM. Becquerel and Edm. Becquerel made some remarks on this paper in relation to the change in colour of stricken trees and flowers.-M. C. Dareste's third part of his paper on the osteological types of the osseous fishes followed, and was sent to the Anatomical and Zoological section.-M. Sainte-Claire Deville then presented a memoir by M. F. Fouqué on some new processes for the proximate analysis of minerals, and on their application to the lavas of the late eruption of Santorin. -The Phylloxera Commission next received a proposal from M. de Wissocq, proposing calcic sulphide and hydrosulphuric acid as remedies for the diseased vines.—M.

M.

THURSDAY, NOVEMBER 28, 1872

FERMENTATION AND PUTREFACTION* T is one of the great attractions of the science of Botany, an attraction common to all the other branches of the study of Nature, that wherever we may happen to be, and under whatever circumstances, something interesting and suggestive is continually brought before the eye and mind educated to understand its teachings, and no true naturalist ought long to be in a difficulty seeking for a suitable subject for illustration At this season of dearth of flowers I hold in my hand a basket of "Duchesse" pears. These have, after their kind, been plucked in France before they were ripe, and some few of them are hard, green, and flavourless; others are soft, full, and mellow, with a rich, delicate aroma-morsels fit for the gods-while others have gone too far, and show -“little pitted speck on garner'd fruit, That rotting inward slowly moulders all."

the

early condition protoplasm, and increasing and multiplying by its agency; and afterwards containing other substances in addition, such as starch and sugar, the products of its assimilation and excretion. These masses of protoplasm with their investing membranes compɔsing the so-called "cells" of the pear, feed, indeed, upon the ternary and more complex compounds produced by the leaves of the pear tree, and are aërated by the fluids which are passing through the tissues of the pear tree; but, secluded from the light, and developing no special colouring matter, their reactions are not in the strict sens: vegetable;" they absorb the organic compounds and breathe the distributed air in the true animal sense, just as Amabæ would do. To take the function of respiration as a test, they absorb oxygen and exhale carbon dioxide, while in the green parts of plants, which alone perform the great function of the vegetable kingdom in keeping up the "balance of organic nature," the exhalation of carbonic acid is in the sunshine entirely masked by the exhalation of oxygen-the product of its decomposition. A green tree may be likened to that wonderful animated tree, one of the oceanic Siphonophora, where a certain set only of the polyps are set aside to feed and to supply nutrition for the whole, while others, identical with these in essential

These changes depend upon fermentation and putrefaction, two processes which are very familiar, and which have of late engaged the attention of some of the most able and skilful men of science, both on account of their vast importance in the economy of nature and of art, and of the singular phenomena which accompany them. These phenomena are very complex and difficult; but chiefly through the patient researches of botanists such as De Bary on the one hand, and of chemists and physiologists who may be represented by Pasteur, Lister, Burdon Sanderson, and Hartley on the other-steady progress is undoubtedly being made towards their solution, although much still remains obscure.

This

The character which most broadly distinguishes the vegetable from the animal kingdom is certainly the power which the former possesses when taken in mass of winning over from the inorganic kingdom binary compounds which cannot contribute directly to the nutrition of animals, decomposing them, and re-combining their elements into organic compounds suitable for the support of animal life. process-the decomposition of water into oxygen and hydrogen, of carbon dioxide into carbon and oxygen, and of ammonia into hydrogen and nitrogen, and the re-combination of these four elements while in a nascent condition into starch, sugar, gum, protoplasm, &c.-is, so far as we know, carried on in plint-cells containing endɔchrome under the influence of light, and in such cells and under such circumstances alone. We thus find that this truly vegetable process is performed by a very small portion of an ordinary plant. The cells of the internal organs of plants and of large pulpy masses, such as these pears, connected with the function of reproduction, are perfectly colourless; simple sacs of cellulose, containing in their * From the Opening Address for the Session 1872-73 to the Botanical Society of Edinburgh, delivered on Nov. 14, by Prof. Wyville Thomson, FR S., President of the Society.

No. 161- VOL. VII.

tate through the water as locomotive swimming-bells.

It is, perhaps, not easy at once to realise this difference in the vital relations of the different parts of the same plant, but it becomes clear enough in the case of pale parasites, for example Cuscuta. The dodder possesses no endochrome cells of its own ; it feeds like an animal upon the organic compounds elaborated by its host. It contributes in no way as a vegetable to the balance of organic nature, and yet it is evidently a plant nearly allied to the ordinary bird-weeds, with all the characters of their well-known natural order.

These "Duchesse" pears are separated from the tree. They were probably separated physiologically before they were taken off, for before we would consider them fully ripe a certain shrivelling takes place in the cells and vessels of the fruit-stalk at a kind of joint, and the communication between the pears and the tree is at first partially and then entirely interrupted. But the pear does not die; it hangs out in the sunshine, and certain chemical changes take place within it, still under the guidance of vital action, sweetening it and developing its flavour. We learn from the beautiful researches of M. Bérard that if fruit be placed to ripen in air or in oxygen gas, a considerable quantity of oxygen is absorbed and an equivalent proportion of carbon dioxide is given off; that, in fact, a notable quantity of oxygen is burned in a true process of respiration. It is calculated by De Bary that the number of plants in which chlorophyll is absent-that is to say, which have no power of decomposing and re-combining the elements of water, carbon dioxide, and ammonia, and which consequently require to have their food presented to them in the form of organic matter-is fully equal to that of green plants, say 150,000. These plants are chiefly fungi. The part they play in the economy of the organic world is wonderful. The moment a plant gets worsted in the battle of life, becomes delicate from uncongenial soil or other circumstances, or gets smothered by a more vigorous rival, they set upon it and burn it.

E