pride that I record that I never heard him utter a word to which the gentlest woman could object, and that I have never found him unequal to any kind of emergency,"

Is the American Museum Journal for OctoberNovember Mr. G. G. MacCurdy, under the title of "Paleolithic Art as Represented in the Collections of the American Museum of Natural History," describes a number of objects acquired in France in 1912 by Prof. H. F. Osborn and the author. Among the most interesting specimens are a series of the tallies, or marques de chasses, which have been interpreted as records of their "kills" by the Aurignacian hunters; a set of perforated teeth, and shells of the Middle Aurignacian period from the Abri Blanchard, Dordogne; a holed limestone fragment, of which the utility is uncertain, it may have been used as a weight; figures of a horse engraved on stone of the Upper Aurignacian period from Roches-de-Sergeac, Dordogne, and of a reindeer on bone from Limeuil.

THE Custom of cross-cousin marriage in South India, recently discussed by Dr. W. H. R. Rivers, is further considered by Mr. F. J. Richards in the December, issue of Man. He arrives at the conclusion that it is based on economic considerations, and, in particular, on the mode of transmission of family property. The Dravidian people follow the rule of matrilinear sucession. They subsequently came under the influence of the intrusive Brahmanical culture, in which the rule of patrilinear succession is followed. The effect of this clash of rival cultures was the desire of the matrilinear community to secure the advantages of patrilinear transmission of the estate; that is to say, the natural desire of the father to provide for his offspring might be secured by insisting that a man should marry the daughter of his maternal uncle, of his paternal aunt, or of his sister. This arrangement would enable a matrilinear community to conform to the patrilinear system of inheritance without fear of dissipating the family property, which is dependent on inheritance on matrilinear lines. The present practice of cross-cousin marriage is thus a compromise between the Dravidian rule of succession through the mother and the Brahmanical rule of succession through the father.

NEARLY the whole of part 6 of the tenth volume of Records of the Indian Museum is devoted to an account of fresh-water and terrestrial oligochatous worms, mainly collected in northern India, with descriptions of a number of new species. The author, Dr. J. Stephenson, of the Lahore College, remarks that the most noteworthy item is the occurrence of Microscolex phosphoreus (a widely spread species, the original home of which was probably in temperate South America), neat Peshawar, at a distance of 700 miles from the sea. Although the dispersal from its original home across the Atlantic and Indian Oceans was doubtless due to the prevalent westerly winds, transport by human agency seems the only explanation of its isolated occurrence in the heart of northern India,

Tur farsberetning of the Bergen Museum for 1913 and the first half of 1014 records steady progress in

all departments during the period under review, I satisfactory incident being the bequest of 7000 iz for general purposes. Numerous additions

the exhibited series of mammals and birds won made, but, judging from some of the figures in t text, there appears room for much improvement the method of taxidermy. Ocean-surveying and u work of biological stations were carried on with gre energy, reports from no fewer than forty-three station being quoted. The contour of the channels of many of the Norwegian fjords is illustrated by a transvers section of the Sognefjord, in which the sudden desce of the sides and the great depth of the middle & well shown.

Dr. W. SØRENSEN has published in French an inportant paper (Kgl. Danske Videnskab. Selska Forhandlinger, 1914, No. 3), on the anatomy of th Solifugida, that remarkable order of Arachnida whi has attracted many zoologists to its study an which formed the subject of a lengthy memoir by t late H. M. Bernard (Trans. Linn. Soc. Zool., 2 ser vol. vi.). The author criticises Bernard's work w some severity, pointing out that the latter's belief the poisonous nature of the Solifugida is unsupporte by facts, and that the structures designated by he as "coxal glands" have no openings on the haunch of the foremost legs, but terminate on short process situated on the dorsal aspect of the appendages of t second pair. These appendages are termed mar: bules" by Sørensen. Considering the anterior pos tion of the excretory organs under discussion, Suren sen's comparison of them with the Malpighian tul of insects, which are outgrowths of the hind-g must remain open to question.

IN a recent issue of the Bulletin of the Imp.: Botanic Garden of Petrograd (vol. xiii., No. 4 G. A. Nadson describes a number of interest ra sulphur bacteria from brackish water in the Get Finland. Two of the forms described are pu from the fact that the cells contain in addition stored sulphur a substance which readily decompen into oxalic acid; these bacteria live in badly acr mud, and by increasing the oxygen supply the oxailike substance was found to increase, and the accur lation of sulphur to diminish, and vice versa. remarkable new genus of sulphur bacteria, ca. Thiosphærella, was discovered, which contained its cells large quantities of a starch-like substan the other forms described are new species of genera Achromatium and Thiophysa.

In a paper which appeared in the Annals of Be ́z (vol. xxviii., No, exii.) and of which we have rec-i a reprint, Mr. S. R. Price describes some res obtained in the study of plant cells by the me of dark-ground illumination, a method hithert little used in botanical work. The method reveals new structural features and is usefu establishing the presence of particles which difficult to see or which are unresolved in illumination, but is very restricted in applicati account of the difficulty of selecting suitable marr for examination. Some of the author's observit. indicate possible lines of work rather than compl

results. For instance, it is generally recognised that protoplasm is a colloidal complex, apparently existing both in the hydrosol and hydrogel state, the two states being spontaneously reversible; the process of germination of fungus spores, followed by the darkground method, showed the gradual conversion of the gel contents of the spore into a hydrosol on absorption of water, and later a formation of a gel might occur again. The nucleus and chloroplasts are probably specialised parts of the plasma with a hydrogel structure, but only in favourable cases could the nucleus be studied. Particles and vesicular bodies (which the author terms "sap particles") were usually found in the cell-sap and showed a continuous Brownian movement; they usually increased in number with decreasing vitality of the cell.

THE problem of the dolomitisation of limestone has received an interesting contribution from Prof. R. C. Wallace, of the University of Manitoba (Compte-rendu of the twelfth International Geological Congress, 1914, p. 875). He regards the concentration of magnesium ions in the solution from which dolomite is precipitated as in many cases the determining factor. This concentration at moderate depths of sea-water may determine whether calcite or dolomite is stable; at a certain concentration of magnesium, calcite goes into solution and dolomite is deposited. In a solution in which calcite is stable, magnesium carbonate may be unstable, and may go into solution until the magnesium ions are sufficiently abundant to produce a precipitation of dolomite. In the case, again, of underground water bringing magnesium into a limestone, a solution may abruptly arise in which calcite is unstable and becomes replaced by dolomite. It will be seen that this view differs from the older one of the mere substitution of magnesium for part of the calcium present in a mass of calcium carbonate.

WE have received from Prof. Eredia a pamphlet entitled "The Organisation of the Service of Weather Predictions in Italy," reprinted from the Rivista Meteorico-Agraria (vol. xxxv., 50 pp.). An experimental system of weather telegrams was instituted in the Papal States from July to December, 1855, and the observations were forwarded to Padre Secchi for examination. His report of the experiment was favourable, but practically the commencement of the service dates from April, 1866, when observations were telegraphed to the central office at Florence. After the removal of the latter to Rome the service was frequently improved, under the direction of Prof. Tacchini, and the daily weather report has latterly again been considerably enlarged. The present director is Prof. L. Palazzo, whose name is well known to many of our readers by the interest he takes in geophysics generally. Prof. Eredia also gives a brief sketch of the origin of the weather service in Europe. With reference to this country he remarks that in 1860 the Astronomer Royal informed M. Le Verrier (Paris) of the proposed establishment of a service on our coasts, and requested an exchange of bulletins. This is strictly true, but it might be explained that the communication was in reply to an inquiry by M. Le

Verrier, which would naturally have been referred to Admiral FitzRoy before being dealt with. The latter issued daily weather reports to newspapers from September 3, 1860, and storm warnings from February 5, 1861. It may be worth while to direct attention to two apparent slips in the last paragraph but one on p. 7 of Prof. Eredia's laborious and useful compilation (with reference to a storm on December 1-2, 1863): Islanda should read Irlanda, and M. Davy is quoted as director of the English service.

IN a review of Dr. Hobson's "Squaring the Circle " in the Bulletin of the American Mathematical Society for November, Prof. R. C. Archibald directs attention to the early use of the symbol by William Oughtred (1574-1660) in his "Clavis Mathematica" of 1631 and in his Theorematum in Libris Archimedes de Spheara et Cylindro Declaratio" (Oxford, 1652). Oughtred employs the symbols 8: to represent the ratio of the semidiameter to the semiperiphery of the circle, although he does not use the symbol separately. He states specifically that R/8 is the semiperiphery of a circle of radius R. Prof. Archibald further directs attention to references to squaring the circle in the Birds of Aristophanes (produced 414 B.C.), lines 1004-5, and in the last canto of Dante's "Paradiso" (canto 33, lines 133-5, in Cary's translation), and he points out that Longfellow, in his translation, gives "to square the circle" as the equivalent of the Italian "Misurar lo cerchio."

IN an article on "The Conic as a Space Element," in the Transactions of the American Mathematical Society, xv., 4, Mr. Roger A. Johnson develops a system of co-ordinates for the conic in three dimension space analogues to the line co-ordinates of Plücker, by treating the conic as a degenerate envelope. It is interesting to note that the problem of the conic in space has been studied for the last sixty years, and that in 1908 the Belgian Royal Academy announced the offer of a prize for a discussion of the subject. It may, however, be pointed out that the problem of the aeroplane in space is at the present time of a far more urgent character, and that the most pressing need is for pure mathematicians who find no difficulty in dealing with cumbersome formulæ as abstract as those which occur in connection with these harmless but unprofitable conics. Still, it is interesting to learn that the totality of conics of a T, that touch two fixed planes, the intersection of which does not meet the axis of the T1, constitute a T, of the most general type.

0

OUR ASTRONOMICAL COLUMN. THE APPROACHING MAXIMUM OF O CETI.-According to prediction, o Ceti or Mira will be at its maximum brightness on February 11 next, but it should be noted that both the star's period and brightness are not always the same at each return to its full brilliancy. As the star remains at its maximum brightness (20 mag.) for about fourteen days, it will be at a maximum on February 4 (approx.). At the present time it is a conspicuous ruddy object in a 4-in. telescope (mag, about 6-0), and its spectrum discloses the strikingly brilliant flutings and the bright hydrogen

this

The

THE ANTWERP ASTRONOMICAL SOCIETY.--In column references have been taken from time to time from the Gazette Astronomique, which was a monthly bulletin of the Antwerp Astronomical Society. last issue (No. 81) appeared in the beginning of September, when the investment of Antwerp had already commenced. A certain number of the members of this society have taken refuge in this country, and many of their British friends have suggested the idea of continuing the publication of this bulletin in London. Many of the latter have already made an effort to solve the financial part of the scheme, and it is due to their initiative that General J. Lerissen (president) and M. Felix de Roy (hon. sec.), on behalf of the society, have issued a circular asking others to contribute. If sufficient support is forthcoming it it proposed to issue the bulletin in both French and English. It will contain, besides notes of observations and of scientific articles, ephemeral notes, reviews of publications likely to interest amateurs, and place at their disposal the working data provided by professional astronomers. Those wishing to help may obtain further information from the hon. secretary at 29 Stamford Street, London, S.E.

SOME RESULTS of the Recent Eclipse Expeditions. -Last week reference was made to the results of the Spanish eclipse expedition to the Crimea during August last, and attention was directed to a red coronal radiation at A 6373-87, which was discovered by M. Carrasco on his photographic plates. This radiation is a new addition to the spectrum of the corona, and, like some other coronal radiations, seems to vary in intensity with the state of solar activity at the time of eclipses. M. Iniguez, the director of the Madrid Observatory, has just forwarded an enlargement (paper) of the region, between Ha and D,, the original of which was taken 13 sec. after second contact, and exposed for 10 sec. This print shows in the first place the sharpness of the images of the arcs, and in the second the clear and prominent arc due to the new coronal radiation. The wave-length is given as 6373-87±0.04 A. units. In the Comptes rendus (vol. clix., No. 23) for December 7 M. Deslandres presents a communication by MM. J. Bosler and H. G. Block with reference to the results of the Meudon eclipse expedition to Strömsund (Sweden). The note is restricted to the results of one part of their programme, namely, the spectrum of the corona. The continuous spectrum of the corona was perfectly regular, and indicated no signs of flutings or Fraunhofer lines, but only gradations due to the sensitiveness of the photographic plate. The well-known green radiation at λ 53037 was entirely absent. In the red part of the spectrum a brilliant and intense new radiation appeared. The wave-length is given as 63745 A. units (to 0-2 A.U. nearly), and agrees well with that determined by the Spanish observers.

GEMINID METEORIC SHOWER, 1914. Mr. Denning writes:-"The weather greatly interfered with observations this year. The sky was, however, favourable on December 8, and a watch was kept at Bristol, but there were few Geminids. These exhibited a welldefined radiant at 106°+31°. The following nights were cloudy and wet, but on December 12 the sky cleared for a few minutes about 10.35. and six

Geminids were noticed. Later, through openings a the clouds, further meteors were recorded, all from the same shower. There were two very distinct radiants, viz., at 109° 33° and 119° + 32° appeared to be about equally active. In 1885 and 1892 the same pair of radiants were very rich, and seemed to prove that the shower is a double one From a comparison of all my observations of the ch system near a Geminorum I conclude the radiant s distinctly a moving one like the Perseids. It seems visible during three weeks from November 25 1. December 16, with a maximum on about December 12. This year I believe the display to have been a very rich one on that date, giving nearly forty meters an hour, and I await observations from places where atmospheric conditions were more favourable than a Bristol. My positions for the radiant are as follea

near the maximum :--

KASHMIR AS A SITE FOR A Solar OBSERVATORY.—Baletin No. 42 of the Kodaikanal Observatory contair a very interesting report by Mr. J. Evershed on " seeing condition as studied by him in the valley o Kashmir. It may be remembered that last year reported very favourably about this valley for solar observations during the months of August 31.4 October, and, contrary to all previous experience n other localities, he noticed that the definition of tr sun was found to be of the best quality throughou the day and on all days that observations were mad there being apparently no marked variations depend ing on the height of the sun above the horizon, no upon the type of weather prevailing. In order to test the conditions in this locality during other mortis of the year, and to make more critical observations both photographic and visual with larger instruments, an expedition was sanctioned by Government in April of the present year, and this report sums un the results obtained during the months of Mas, June, and July. A scheme of operations was dis ranged so that comparisons at Kashmir could te made with the experiences at Kodaikanal. For a detailed account of the results the reader must b referred to Mr. Evershed's report, but the following brief statement of the main result is as follows:— Taking a scale of seeing as very bad definition :, bad 2, fairly good 3, good 4, and so perfect that my tremors can be perceived in the 8-in. solar image projected on a screen attached to a portable instr | ment as 5, then it may be stated approximately th the mean seeing at Kodaikanal for the whole y would hardly reach 2, whilst that in Kashmir valley would probably exceed 3.9. The number of days when the seeing ranged between 4 and would be ver much larger in Kashmir than in Kodaikanal. photographic work was found entirely to confirm 12visual observation, and, as he states, "indicates the enormous possibilities of progress in the study of solar physics which an observing station in Kashmi: Valley would present." As the chief factor in solar research is the quality of the "seeing," the importance of the above conclusion cannot be put aside,

T

COLLIERY EXPLOSIONS AND COAL-DUST.

UNDER the title of "Great Colliery Explosions and

their Means of Prevention" (London: The Colliery Guardian Co., Ltd.), Dr. W. Galloway has collected into a small volume a number of papers contributed by him between the years 1872 and 1908 to various publications; these were so scattered that their logical sequence was not always easy to trace, and they gain greatly by being presented in their order and gathered within the covers of a small volume.

The first two papers deal with the connection between colliery explosions and the state of the barometer, and showed, what no one probably doubts to-day, that there is a greater danger of firedamp explosions with a falling barometer than under any other atmospheric conditions. The next paper gives an account of a series of experiments which demonstrated that a violent atmospheric concussion, such as that produced by a shot, can force flame through the gauze of a safety-lamp, so that a lamp, which would be quite safe in a quiescent explosive atmosphere, may initiate an explosion if the same atmosphere is violently disturbed. This fact, like those above referred to, is a matter of such common knowledge to-day amongst miners that they are apt to forget that there ever was a time when it was not known, and it is as well that they should have at hand a reminder as to who it was that first discovered this very important fact.

The remaining papers are perhaps of higher interest than those already mentioned, as they all deal with the part that coal-dust plays in propagating colliery explosions. For a long time the coal-dust danger was either neglected or flatly denied even by the highest mining authorities, and Dr. Galloway deserves the greatest credit for the part he has played in forcing its recognition upon the mining community. It is evident from a perusal of the papers here collected that it was only gradually that the gravity of the danger of coal-dust explosions impressed itself upon Dr. Galloway himself, and that it was quite a long time before he could convince himself that coal-dust was dangerous in the entire absence of fire-damp. Thus in 1876 he disagrees with the opinions expressed by a French engineer, M. Vital, who held that finely divided coal-dust may of itself alone (i.e. without firedamp) give rise to disasters, and he states his definite conclusion that a mixture of air and coal-dust is not inflammable at ordinary pressure and temperature" (p. 57), and goes on to show that when as little as o 892 per cent. by volume of fire-damp is added the mixture becomes inflammable. Already at this date, however, Dr. Galloway advocated the watering of the roadways in collieries so as to keep down the dust. In 1879 Dr. Galloway had apparently modified his views to some extent, for he then wrote: "It is probable, moreover, that some kinds of coal-dust require less fire-damp than others to render their mixture with air inflammable; and it is conceivable that still other kinds may form inflammable mixtures with pure air (p. 73). In his first paper in 1882 he still seems to consider the presence of a minute proportion of firedamp, too small to be detected by a safety-lamp in the ordinary way, which he calls the "latent" fire-damp, indispensable to the formation of a dust explosion, he continued to experiment, and in his second 1882 paper he wrote that his experiments "show concluSively, I think, that fire-damp is altogether unnecessary, when the scale on which the experiments are made is large enough" (p. 111). It is important to note that Dr. Galloway reached this conclusion after six years of continuous experiments, in direct contradiction to his earlier views on the subject, and this fact should of itself have inspired confidence in the matured opinions that he expressed.

but

The remaining papers in this volume are devoted to an elaboration of this coal-dust theory, but though of undoubted importance, they are less so than the abovequoted series in which Dr. Galloway showed by direct experiment that coal-dust and air form an explosive mixture even in the absence of inflammable gas, and the fact that he was the first to furnish experimental proof of this has established his reputation as an original, accurate and painstaking investigator of colliery explosions; this little volume shows clearly enough the extent to which he has laid the coal-mining community not only of this but of all other countries under a deep debt of gratitude. H. L.

THE EDUCATION IN LONDON OF REFUGEES FROM FOREIGN UNIVERSITIES.

A FEW weeks ago (NATURE, November 26) we

gave an account of what is being done to establish an informal Belgian university at Cambridge, for students of the University of Louvain and other universities affected by existing military operations. Both the Universities of Oxford and Cambridge have, so far as we understand, offered a generous hospitality on a large scale to both the staff and students of Belgium universities, but while affording them every facility for quiet study, have not attempted to bring them systematically within their own system. The University of London, on the other hand, is putting at the service of refugee students not merely the teaching facilities of its two incorporated colleges, but also the right to enter its degree courses and to obtain its degrees on exceptionally favourable terms. It is allowing a partial or total remission of fees both for full teaching courses in expensive laboratory subjects, such as engineering and preliminary and intermediate medicine, and for entrance to examinations. It has further made special concessions as to both the matriculation and intermediate examinations, which will make it possible for the students to answer questions in French, and have their knowledge tested on the lines of education they have previously received in their own universities. If the Privy Council approve of the Amendment of Statutes which the Senate of the University is referring to them, a clever student who has come over to London from Belgian or French universities this autumn, will be able to pass the examinations in lieu of matriculation and intermediate by the early spring, and enter at once on his final course.

This interesting experiment to enable deserving students of the allied nations to obtain actual English degrees entails extraordinarily severe work on the administrative and teaching staff of the colleges. King's College has seventy-four of such students, University College sixty-seven, and the Imperial College a certain number. None of them knew English to start with, and special classes have had to be arranged to teach it them. The courses in foreign universities differ greatly from those of English universities, as well as from each other, and infinite care has had to be taken to discover the exact stage in each subject which a given student has reached., In engineering, for instance, in which King's College alone has forty-two such students, the standard of applied mathematics is much lower in the earlier stages in Belgium than in England, while that in pure mathematics is higher. Even allowing for the assistance of the Belgian professors who are being called into council, it is not above the mark to say that the time taken over each refugee student is as much as that over ten English students. Apart from the academic work, the hospitality which the senior common rooms of University and King's Colleges

have extended to these students, many of whom are for the present quite without funds, cannot be left out of account. In regard to the Jewish students, who form a large proportion of the whole, and who are mostly Russian subjects studying at Liège or Ghent, valuable help has been received from the Central Jewish Committee.

This effort, however great the tax it imposes on the colleges, is worth making. It will enable Belgians who are medically unfit to go on active service, and Russians whose military service begins at the end of their university career, to obtain their professional qualifications during the war, and thus fill the depleted ranks of doctors and engineers in their respective countries. It will also spread a knowledge of English university education on the Continent, and not improbably make the University of London an international, as it is already an Imperial, centre of university education.

THE PRODUCTION AT WILL OF EITHER FUNGUS-GERMS, FLAGELLATE MONADS, OR AMEBE FROM THE ULTIMATE SEGMENTS OF SMALL MASSES OF ZOOGLEA.

ΑΝ

N illustrated article dealing with this question of the heterogenetic origin from small Zooglea masses of Fungus-germs, Monads, or Amabæ, written by me, appeared in NATURE of November 24, 1904. That article was prepared at short notice in consequence of a short letter on "Archebiosis and Heterogenesis," which appeared a fortnight previously, and at a time when I was not specially working at this subject. Of late I have been doing much work in this direction, and have made out many very important new points, and can now speak with more precision concerning the changes generally, and the modes of obtaining them.

My results were received with great scepticism, and no bacteriologist has been induced to attempt either to confirm or refute them. The possibility of "infection" has so dominated them, that they have refused to consider the question. Of late, however, three bacteriologists have accepted my request that they should allow me to demonstrate to them my position by their examination of actual specimens. This they did, separately, and as a result neither of them was able to doubt that the Fungus-germs, the Monads, and the Amoeba were, in truth, derived from the ultimate segments of the Zooglal masses; nor did they suggest that the very similar developmental changes to be seen in hundreds of Zooglœal masses taken from their respective scums could possibly be accounted for by "infection."

Only one of my friends had any interpretation to suggest in opposition to my own. He started the supposition that what appeared to be bacterial aggregates might "possibly," in spite of their appearance, not actually be of that nature. He suggested that, though taking the guise of bacteria, and though all were similar in appearance, they might nevertheless be some hitherto unknown progenitors of Fungusgerms, of Monads, and of Amoeba which had aggregated as Zooglœal masses, and subsequently given rise to their respective products.

This wild supposition may, at all events, be taken as an indication that its author could not doubt the fact of the different products coming from the ultimate segments, or imagine that "infection" could account for what he had seen. It was started by one who was absolutely opposed to the very notion of heterogenesis. He was subsequently able to find absolutely no support for his "possibilities," and after a

futile search frankly admitted that only bacteria. Zoogleas were known, apart possibly from others. an algoid type.

The current notion among bacteriologists concer ing the nature and mode of origin of Zooglœas is th adopted by R. Muir in the article, "Bacteriology." the last edition of the "Encyclopædia Britannica (vol. iii., p. 161), in which he says:-"The Zoogl is now known to be a sort of resting condition of the Schizomycetes, the various elements being glued together, as it were, by their enormously swollen and diffluent cell-walls becoming contiguous."

But bacteriologists do not seem ever to ha examined the small masses that form in the segm on the surface of a hay infusion. I have been unat to find any reference to them, or of processes of mentation occurring in any other Zoogleas. I canno think that those with which we are now concerned are formed in the manner above indicated. evidence seems rather to show that as the bacteria

All the

rapidly multiply they also excrete the jelly-like glas material in which they are subsequently found to be

imbedded.

Preparation of the Infusions.

One of the important new points recently ascer tained is that I can prepare two small infusions at the same time from the same sample of hay, and by allowing one to infuse for three hours at a temperature of 90° F., can feel confident that in the course of three to five days the ultimate products of segmentatio of the Zoogloeas that form can be made to yisd Monads or Amoeba; while if the other is infused for the same time at 98° F. no Monads or Amoeba will appear, and the ultimate Zooglœal segments, though formed, and very similar in appearance, will remain apparently stationary for eight to thirteen days, and then begin to show themselves as multitudes of brown Fungus-germs.

It is best to use comparatively new hay, and no that of the previous season. 1 take a small portion and having cut it into -in. lengths, place it in 2-z beakers to which water is added just sufficient to cover it. The proportion of the two I have found to be a little more than 30 grains to the ounce of water As soon as the infusions have been made they are filtered through No. o Swedish paper (so as to exclud encysted Kolpoda and the great majority of Funcus spores) into common one-ounce porcelain pots, unt they are about half-full-the depth of the infusion being then only a little more than half an inch. The scum which ultimately forms will be thin, and therefore much more favourable for examination than if it had been thick and formed over a greater depth of infusion. The covers are replaced on the pots, and the dates and temperatures at which the infusions hav been made are marked thereon. These covered pots are then mostly kept at room temperature, 62°-64° F.

Examination of the Scum or Pellicle.

The pots are not usually opened until two days have elapsed, as it would be only during the last twelve hours that any very distinct scum begins to form, and that a few very small Zoogloas may be found scat tered through it. By the end of the third day the Zoogleas may be very numerous, and will be foun to vary much in size and shape. An example illutrating a rather later stage is shown in Fig. 1, in which the little masses are seen to be extremely numerous. Many of these early Zooglas already show primary processes of segmentation.

In order to examine the scum a small portion is taken up on the point of a scalpel and rotated off on to a drop of distilled water. If thereafter it should be desired to preserve the specimen some 5 per rent