Catalogue of the Lepidoptera Phalaenae in the British Museum. Vol. viii., Catalogue of the Noctuidae. By Sir George F. Hampson, Bart. Pp. xiv+583; pls. cxxiii-cxxxvi, and 162 text-figures. (London: British Museum, Natural History, 1909.) Text, price 155.; plates, price 12s.

WE have again to congratulate Sir George F. Hampson and the Trustees of the British Museum on the completion of another volume of the great catalogue of moths, which bids fair to surpass even the catalogue of birds in extent and importance. Vol. viii.,

now before us, is the fifth volume devoted to the

Noctuidae, and the second of the great subfamily Acronyctinæ, which it will require a third volume to complete. Fifteen subfamilies of Noctuidae were indicated by the author at the commencement of his work; possibly he may find it necessary to increase the rumber before its completion. The Acronyctinæ,

Occupying three volumes, is only the fourth subfamily out of the fifteen, but, in the sense in which the author employs it, it is, perhaps, the most extensive of all. The remaining subfamilies, with three or four exceptions, appear likely to be of very much

smaller dimensions.

Works of this character are far too costly to be

undertaken by private enterprise, and though the price at which they are published by the museum cannot be remunerative, the cost of an extensive work issued in successive volumes soon becomes prohibitive to private students.

Hence we would urge on the librarians of public libraries and museums at home and abroad to secure sets of such publications as those of the British Museum before the volumes become too numerous, and before any of the earlier ones go out of print. Many of the earlier publications of the Museum were issued in comparatively small numbers, and several are now scarce and difficult to obtain. Sometimes early volumes have been exhausted even before the whole series has been completed. This is another reason why public libraries, to which they will always be valuable, should not neglect to add them to their shelves as soon as they appear.

The Geology of South Africa. By Dr. F. H. Hatch and Dr. G. S. Corstorphine. Second Edition. Pp. xvi+ 389. (London: Macmillan and Co., Ltd., 1909.) Price 21s. net.

THE general scheme of the book remains the same as in the first edition, but the authors have skilfully rearranged portions of the original subject-matter and have made those additions which the rapid advance of geological investigation in South Africa since 1905 has rendered necessary.

To digest and sift the numerous official and unofficial reports dealing with the geology of South Africa is no easy task, and with respect to the stratigraphy of these regions, the authors have evidently spared no pains to bring the book up to date. They, however, almost entirely ignore the many interesting problems connected with the origin and development of the present physical features, of which striking examples have been illustrated and described in the reports of the surveys of Cape Colony, of the Transvaal, and of Natal, as well as in other publications. This is an obvious omission in a work entitled "The Geology of South Africa." In dealing with the correlation of the widely scattered formations, the authors speak in a guarded

manner, but their suggested correlation of the older formations will not pass unchallenged. The illustrations, of which many are new, retain a high standard of excellence. The figures illustrating the fossils of the Karroo are the least attractive, and are hardly representative, especially with respect to the well-known and interesting reptilian remains. of place-names is overburdened by a superfluity of The general index is far too meagre, and the index mere page references of more annoyance than assistance to the general reader.

Handbook for Field Geologists. By Dr. C. W. Hayes. Pp. ix + 159. (New York: J. Wiley and Sons; London: Chapman and Hall, Ltd., 1909.) Price 6s. 6d. net.

THE preface states that this work originated in a handbook printed in 1908 for distribution to members for copies of this were so numerous that it was reof the United States Geological Survey. Requests written, omitting those instructions which apply only to members of the Government Geological Survey, and enlarging upon certain features which will be of service to students preparing for work in field geology. In spite of this declaration the book still contains Government Survey in the United States, but is, bemuch which is only applicable to members of a sides, a very practical little handbook, the treatment of the problems connected with the determination of dip, thickness, and depth of beds being perhaps the least satisfactory part. These problems, if properly put, are of great simplicity; but the beginner, trusting to Dr. Hayes, might well conclude that there was some subtle difference between the dip of a fault plane and the dip of a stratum, and that problems which may be tackled in the one case are insoluble in the other.

An attempt has been made to get over the difficulty of making the same work at once a beginner's guide and an expert's vade mecum by dividing it into two sections, and of the two the latter seems better done. The schedules of subjects to be noticed in special investigations have their use in refreshing the memory whenever a fresh piece of work is entered on, but the ideal geologist's pocket-book is yet unpublished. Engineers and architects have their little books crammed with information cut up into pieces, each complete in itself, so that temporary lapse of memory on any particular point can be rectified, or reference made to figures which the human brain cannot carry, but which must be accurately known if required at all. Geologists, on the other hand, whether on account of the smallness of their number or their supposed addiction to dilettante methods, are condemned to wade through a mass of matter, with which they are familiar, to obtain the particular piece of information of which they are in search.

Physiology: a Popular Account of the Functions_of the Human Body. By Dr. Andrew Wilson. Pp. vii+128. (London: Milner and Co., Ltd., n.d.) Price Is. net.

As a contribution to scientific literature this book is negligible; as a popular exposition of the elementary principles of physiology it is untrustworthy. It is no part of a reviewer's duty to enumerate the errors scattered through it; it will be sufficient to take one as a sample. "The red blood corpuscles are also carriers of carbonic acid gas to the lungs... and the darker colour of impure or venous blood is explained by the fact that when carbonic acid gas unites with the hæmoglobin a darker hue is produced" (p. 64). A first year's student knows better than this. It would be better to leave the writing of physiological text-books to those who know something of physiology. W. D. H.

LETTERS TO THE EDITOR.

[The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.]

Magnetic Storms.

IN supplement to my letter in the last issue of NATURE I may add that if a solar outburst, acting in the way supposed, causes a magnetic storm which lasts eight hours, the effective influence of the whole group of electric streams at the distance of the earth must extend over a breadth of about six million miles; so that if simply conical, with vertex at the sun's centre, the angle of the cone would be four degrees. Projected back to the surface of the sun, this would correspond to what we may call a spot about one-thirtieth of the visible disc in diameter; but, inasmuch as the trajectory of the particles in the beam would be slightly curved, the size of the actual solar eruption could be much less.

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Until the main outlines of the view advocated are approved by those most competent to judge, it is useless to enter into further details.

I regret to notice a numerical slip-fortunately unimportant, since it affects nothing else-in the top line of my letter on p. 426, where the current equivalent should be expressed, not in hundred thousands, but in hundred millions of amperes-an order of magnitude which is "reasonable " rather than surprisingly moderate." October 9. OLIVER LOdge,

on the

Magnetic Storms and Solar Eruptions. I HAVE read Sir Oliver Lodge's letter (NATURE, October 7, p. 425) on the above subject with some surprise. The emission theory which he supports, and which he claims to have originated, regards kathode rays from the sun as the electric carriers, and so is presumably the same as has been actively advocated by Prof. Kr. Birkeland for a number of years. He seems, however, to be unaware of the existence of Birkeland's volumes 1 subject, and of the numerous numerical calculations therein contained. He also makes no reference to the important mathematical work of Prof. Störmer, which cannot, I think, be disregarded by anyone whose theory postulates the introduction of charged particles from without into the earth's magnetic field. The general idea that magnetic storms are due to some action arising in the sun goes back to at least the time of Broun and Balfour Stewart, and different forms of the emission theory have naturally presented themselves to various minds independently, as Röntgen, kathode, and other rays came successively under our ken. It is when we come to details that real troubles arise. Most people, I take it, have little difficulty in believing in a general way that the changes of declination experienced at a single magnetic observatory, say Kew, during a magnetic storm can be accounted for by a stream of electrons in the magnetic meridian, provided it is possible for the direction and intensity of the stream to be altered at frequent intervals. One doubts this just as little as that the motion of the magnet of the declination magnetograph at Kew on September could be reproduced with the aid of a copper wire, a single battery cell, a commutator, and a resistance box. Those who have seen Störmer's calculations and studied Birkeland's volumes will realise, however, that to be garded as an advance of knowledge at the present day, a theory must afford an explanation, not merely of what is taking place in a single magnetic element at a single station, but of what is taking place in all three elements at a number of stations. Coming, now, to Sir Oliver Lodge's own calculation, it seems based on an inadequate idea of the phenomena of the late storm, derived from a description of one or two of the more striking changes at Kew as recorded in your columns and those of the Times. It is rare for a disturbance to be limited to the declination, i.e. for the disturbing force to be wholly perpendicular to the magnetic meridian. The component in the magnetic meridian is, as a matter of 1 "Expédition Norvégienne de 1899-1900," and "The Norwegian Aurora Polaris Expedition, 1902-3," vol. i.

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fact, usually the larger. A vertical component is al usually present. A magnetic storm does not usuall consist of a disturbing force in a fixed or nearly fix direction, waxing and waning. Each of the three elemente usually exhibits values both above and below the norme, and not infrequently there are many excursions on bot sides of the mean. This will, I think, be readily reg nised by anyone who consults the reproduction of the Stonyhurst curve of September 25 in your columns and the Kew curves in the Electrician. After inspecting the curves it will, I think, be recognised that it is quite ut of the question to limit the passage of the imagina solar jet, as Sir Oliver Lodge does, to the fifteen minuts near the end of the storm, when there occurred the prominent declination oscillation to which he has confined his attention. Even whilst this oscillation took place, :: was far from representing the total disturbance. Simultaneously with it, but partly overlapping, as is often the case, there was a very large change in progress the horizontal force. Those looking at the curves will. I think, agree that if there was a jet such as Sir Oliver Lodge supposes, its time of transit took, not fifteen minutes, but at least nine hours. His estimate of th diameter of the cone thus requires multiplication by with a consequent multiplication of the cross-section, if it were circular, by 1295. Large as this may appear, the jet theory requires it to be often exceeded, as the storm of September 25 was an unusually short one. The average duration of the storms in Mr. Maunder's Greenwich from 1882 to 1903, was almost exactly thirty hours, so that the cross-section of the average storm-jet would be naturally fully 14,000 times that given by the calculation in your columns. The really crucial thing is that the magnetic disturbances which occur simultaneously a different stations are inter-related. It is in accounting satisfactorily for these inter-relations that Birkeland, whe has given years of thought to the subject, encounters his main difficulties.

In pointing out these facts, I am not expressing arv opinion for or against any or all of the emission theories. What I think is really called for at the present moment is a reservation of judgment as to theories, and a more minute study and inter-comparison of the records from different observatories with a mind as unbiased as possible by preconceived ideas. C. CHREE October 9.

Fireball in Sunshine.

WITH the sun shining in a beautifully clear sky on October 6, at about 9.40 a.m. a large meteorite passed over central England, and was well observed from many widely distant stations. People noticed it in Norfolk, Suffolk, Gloucester, Somerset, and other counties, but the observations, owing to the absence of visible sky marks, are not very definite.

The meteor was brilliant; it had a slow motion, traversing a long path in about four seconds, and it lett a luminous trail of short duration. An observer at Brisel says it burst with rocket-like effect at the finish. The meteor had a radiant in the south or south-east sky, but the place is uncertain. At the time of the observation Leo was on the meridian and Virgo and Bootes near.

At Cottesbrook, Northamptonshire, a loud detonation followed the meteor in four minutes, which corresponds to a distance of fifty miles. At East Haddon, Holdenby, ard other small towns and villages north-west of Northampton the noise of an explosion was heard, doors creaked, windows rattled, and people ran out of their houses in terror, thinking that an earthquake had occurred. The final disruption of the meteor evidently took place over the region ten or fifteen miles north-west of Northampton, and its direction of flight was from S.S.F., so it must have passed over, or nearly over, London. Further observations will be exceedingly useful if they are sufficiently exact to be utilised. W. F. DENNING

jome may be of very ancient date. Wells are so rare n ancient camps on the downs that ponds were probably the chief source of water supply. Why straw was first used, and how it was first used, are likely o remain unanswered satisfactorily. A description is given of a small experimental pond which the author made. The foundations were composed of woodwool resting on a chalk base, followed by straw and wooden planks, with puddled clay thereon. Further investigations are promised, and no doubt the success or otherwise of the pond will form the subject of a future paper.

In the discussion which followed the reading of the paper, Dr. H. R. Mill claimed that rain is the principal factor in filling the downland ponds, and suggested that the reason why the lowland ponds the more quickly dry up may be that they are not so carefully made watertight as those on the higher ground.

ARTIFICIAL PARTHENOGENESIS.1

THE HE development of biology into an experimental science is nowhere better illustrated than in the important researches on artificial parthenogenesis which we owe largely to Jacques Loeb, and biologists will welcome heartily the little book in which this distinguished author gives an account of the subject. Prof. Loeb informs us that the object of his investigations was to transfer the problem of the fertilisation (Entwicklungserregung) of the animal egg from the domain of morphology to that of physical chemistry. He recalls the fact that it is only about sixty years since it was first firmly established that the animal egg with the exception of a few cases-can only develop into an embryo after fertilisation by the entrance of a spermatozoon. Various interpretations have been placed upon this process. O. Hertwig maintained that the essential feature of fertilisation was the union of the male and female pronuclei in the eggcell, and the observation of this union was doubtedly of the greatest importance, especially from the point of view of the theory of heredity, but it gave us no real insight into the nature of the stimulus which evokes as its response the segmentation of the egg. Boveri, indeed, maintained that the union of the two pronuclei had nothing to do with providing this stimulus, and was able to show that an enucleated egg may develop after fertilisation by a spermatozoon. According to Boveri the centrosome is the organ of celldivision, and the unfertilised egg cannot develop because the centrosome is wanting. A new centrosome is introduced by the spermatozoon, and then celldivision or segmentation commences.

un

Loeb, however, maintains that the development of the egg is a chemical process, depending mainly on oxidation, in which there takes place a synthesis of nuclear material from constituents of the cytoplasm. He accordingly regards the Boverian hypothesis, in which a purely mechanical rôle is assigned to the centrosome, as inadequate to explain the nature of fertilisation. His earliest experiments consisted in treating the eggs of a sea-urchin with sea-water, the alkalinity of which had been increased by the addition of soda-lye. In such water the eggs segmented once or twice, but did not develop further. On the other hand it was found possible to cause the unfertilised eggs to develop into larvæ by placing them for a couple of hours in hypertonic sea-water-sea-water,

"Die chemische Entwicklungserregung des tierischen Eies (Künstliche Parthenogenese)." By Jacques Loeb. (Berlin: Julius Springer, 1997. Price marks.

that is, the osmotic pressure of which had been raised about 60 per cent. by the addition of some kind of salt or sugar. This apparently purely osmotic stimuiation of the egg was subsequently found to comprise two factors, viz., the loss of water by the egg, and the concentration of the hydroxyl-ions of the hypertonic solution. It was also found that the hypertonic solution can only stimulate the egg to development if it contains free oxygen in sufficient quantity.

The author next succeeded in producing larvæ from unfertilised eggs of Chatopterus by means of potash and acids without raising the osmotic pressure of the sea-water.

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It has long been known that the eggs of many animals, immediately after the entrance of the spermatozoon, form a "fertilisation membrane" on the surface. We used to be told that this membrane served to prevent the entrance of additional spermatozoa. Loeb attributes to it a much deeper significance. He finds that in the case of osmotically fertilised " eggs no membrane-formation takes place, but a short treatment with a monobasic fatty acid causes the formation of a typical "fertilisation-membrane" in all the eggs of Strongylocentrotus. If such eggs are then placed for a short time in hypertonic sea-water they all develop into larvæ. The artificial membrane-formation by itself, however, in this case only causes the eggs to commence their development without being able to continue it

The membrane-formation is regarded as the most important factor in fertilisation. It has also, however, a deleterious effect, a tendency to cytolysis, which requires to be counteracted by treatment with a hypertonic solution, or in some other way. In some species the artificial membrane-formation alone is sufficient to bring about the development of the eggs to normal larvæ, the injurious cytolytic effects being less marked than in the sea-urchin. That it is the membrane-formation and not any other action of the fatty acid which brings about the development of the egg is evident from the fact that membranes produced in any other way have the same effect.

The author attributes a like importance to membrane-formation as the essential factor in the normal fertilisation of the egg by the spermatozoon, and proceeds to inquire what substances and agencies determine such formation. Membrane-formation may be regarded as a stage in the cytolysis of the egg, and all cytolytic agents will cause membrane-formation. Clearly the cytolysis must be arrested in some way after the membrane has been formed, otherwise it will lead to the destruction of the egg. Loeb maintains that in the natural fertilisation of the egg the formation of the fertilisation membrane is brought about by a "lysin," carried by the spermatozoon, which also brings with it a second substance which serves to counteract the evil effects of membraneformation.

Such is the essence of the "Lysin Theory " of fertilisation. As an attempt to interpret biological phenomena in terms of chemistry and physics, it is of the greatest interest, though the point of view from which its author regards the phenomena of fertilisation may not be the one which appeals most strongly to students of biology.

We do not doubt that a new edition of this extremely interesting work will shortly be called for, and we hope that it may be found possible to publish it simultaneously in German and English. Not the least valuable feature of the book is, to our mind, the introduction of twenty-one pages, in which a concise résumé of the entire subject is given.