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Mr. Wilkinson speaks of wood-pigeons as forming a common article in the dietary of the kestrel. From the great size and weight of this bird, in relation to the kestrel, one cannot resist a suspicion that he is really referring to the turtle-dove. The wanton destruction, both of the kestrel and the hobby, by gamekeepers, gives one cause for rejoicing that at least occasionally they escape the varied and often brutal engines of destruction which, in spite of Preservation Acts, are still in common use. This persecution is the more reprehensible because these birds, like owls, destroy immense numbers of mice and rats, whereas the amount of game destroyed is negligible, as anyone can discover for himself who will take the trouble to examine the pellets thrown up according to the custom of raptorial birds. Not one pellet in ten thousand will be found to contain remains of partridge or pheasant.

THE annual report of the Scottish Marine Biological Association for 1914 contains a record of the work done at the Millport Marine Station during that year. The most important investigations to which reference is made in the superintendent's report are those of Dr. J. F. Gemmill on the development of Asterias rubens, the detailed paper on which has appeared in the Philosophical Transactions of the Royal Society. Other work of interest is the systematic investigation of a sandy shore undertaken by Mr. R. Elmhirst and Prof. L. A. L. King, and the study of the regeneration of legs in Crustacean Decapods by Mr. J. H. Paul.

Two papers by Dr. C. G. Joh. Petersen make up the Report of the Danish Biological Station, No. xxiii, 1915. The first is on the animal communities of the sea-bottom in the Skagerak, the Christiania fjord, and the Danish waters, and is a continuation of similar studies already published by the author dealing with the communities found in Danish waters. The investigations were made by means of the bottomsampler designed by Dr. Petersen. The second paper is called, "A Preliminary Result of the Investigations on the Valuation of the Sea," and in it an attempt is made to give numerical estimates of the annual production of various marine organisms, including fishes, in the Kattegat. Whilst undue importance is not intended to be given to the actual figures put forward, the method followed by Dr. Petersen is one which will doubtless be capable of great development in the future.

THE July number of the Quarterly Review contains an article by Mr. Stephen Reynolds dealing in a general way with the question of the inshore fisheries, but referring specially to the two Departmental Reports published in 1914. The author traces the various causes which have led to the decadence of sea-fishing by small boats on various parts of the coasts of England and Wales. In his opinion the decentralisation of administration brought about by the creation of the District Fishery Committees has had a prejudicial effect. These bodies are not really representative of the fishing interests; and they are, with one or two exceptions, unprovided with sufficient resources to enable them to carry on constructive work, scientific research,

or the legal defence of existing fishing rights. Their work has been mainly that of the imposition of restrictions and prohibitions on methods of fishing. The committees are subject to the general control of the central authority (the Board of Agriculture and Fisheries), but the latter possesses no power to initiate legislation. The Inshore Fisheries Committee, which reported in 1914, recommended the practical abolition of the District Committees and the transfer of the actual power of regulation to the central authority. It also recommended various schemes of local organisation and co-operation, and with the assistance of the Development Fund some of these have been begun. Mr. Reynolds describes very shortly the steps that are being taken in Devon and Cornwall to revive and stimulate the smaller fisheries, mainly by means of loans of money to the men. A grant from the. Development Fund has also been made to the Fisheries

Organisation Society, so that this body has been able to provide a staff for the promotion of the industry.

IN the July number of the Journal of Anatomy and Physiology Prof. F. Wood Jones makes a welcome contribution to our knowledge of the external genital system of Chelonian reptiles. He regards the external genitalia of turtles and tortoises as representative of a very generalised and primitive type. The commencement of the Chelonian type of copulatory organ is to be seen amongst certain of the Amphibia; the same type occurs as an embryological stage in mammals. The author regards it as probable that "the mammalian stock arose early from some basal meeting point of the Amphibians and the sculate reptiles."

IN 1913 Sir Edward Schäfer accepted an invitation from the Leland Stanford Junior University, California, to deliver the Laue medical lectures. He chose for his subject the endocrine glands-that is, the organs of the body which form internal secretions. His name is so closely associated with researches on these glands, especially the adrenal and pituitary bodies, that his choice was an almost obvious one, and those who did not have the opportunity of hearing Sir Edward are now able to read his lectures, as in a pamphlet of ninety-four pages, which is simply they have been' published by the Stanford University packed with information expressed in lucid style, and admirably arranged. We can highly recommend the booklet to those who wish to obtain a brief history of our knowledge on this interesting subject, and an authoritative statement of the stage it has reached at present. We note that the author employs his new nomenclature for the substances usually grouped together as hormones; so far the new words have not "caught on," but perhaps the present publication will stimulate other physiologists to adopt them. The same mail brings us another publication in the same series, "The Hæmolymph Nodes of the Sheep," by A. W. Meyer, from the anatomical department of the Stanford University. The subject is not altogether unrelated to the endocrine glands, though it is at present doubtful whether these nodes, or accessory spleens, as they may roughly be termed, form any internal secretion. Dr. Meyer, however, treats the subject mainly from the anatomical point of view, and

his paper is illustrated with some very beautiful drawings.

AN interesting contribution to our knowledge of abnormalities in the reproduction of vertebrates has been made by Mr. R. Curtis in a paper on the relation of simultaneous ovulation to the production of doubleyolked eggs in the domestic fowl (Journ. Agric. Research, vol. iii., No. 5). Such eggs may have (1) the entire set of egg-envelopes common to the two yolks, or (2) the chalaziferous layers separate and the thick albumen common, or (3) entirely separate albumen envelopes and only the membrane and shell common. Of the eggs examined, 71 per cent. belonged to the second type. In only very few cases was there evidence of simultaneous ovulation, and the author believes that "the fusion of follicles and a resulting common blood-supply is by no means the usual cause for the production of a double-yolked egg." In the Report of the Maine Agric. Exp. Station for 1915 (pp. 65-80) Dr. R. Pearl and Mr. F. M. Surface describe a cow which assumed some of the secondary characters of the male, developing thickness of neck and smoothness of rump, and also behaving in many respects like a bull. This animal had been, before the strange change, a normal cow, having borne three calves and shown a high milk record. Post-mortem study showed cystic degeneration of the ovaries in which no corpora lutea were being formed. Hence the authors conclude that the corpus luteum is of importance in maintaining female secondary characters in full development.

WE have received a copy of a paper on the fungus diseases of Hevea brasiliensis contributed by Mr. T. Petch, Government mycologist, Ceylon, to the International Rubber Congress held at Batavia yast year. It is reassuring to read that notwithstanding the vast areas under Hevea cultivation, often under bad conditions, no very serious parasitic fungus has as yet been noticed. Fomes semitosus, the root disease, first recorded by Ridley at Singapore in 1904, which was much feared, is proving to be of minor importance as the plantations increase in age and as the jungle stumps on which it flourishes disappear. The stem diseases, of which six have been recorded, are perhaps the most dangerous. Three of these, pink disease (Corticum salmonicolor), die-back (caused especially by Botryodiplodia theobromae), a well-known cacao disease, and canker due to Phytophthora faberi, are especially to be feared. It is suggested that Bordeaux mixture may prove effective as a preventive to canker.

THE annual report of the agricultural and horticultural research station of the University of Bristol, otherwise known as the National Fruit and Cider Institute, at Long Ashton, contains a series of papers on cider and perry, mainly by Prof. B. T. B. Barker and Mr. Otto Grove; papers on the treatment of plant disease, by Mr. A. H. Lees; on economic mycology, by Mr. S. P. Wiltshire; on fruit culture trials, by Prof. Barker; and on soils and manures, by Mr. C. T. Gimingham. Among these papers one on the use of pure yeast in the fermentation of cider by Mr. Grove, and a note by Mr. Gimingham on the use of the waste from saw-mills as a source of potash have a

general interest. The fact that the ash or flue-dust from saw-mills which burn wood as fuel contains from 5 to 9 per cent. of potash, is not generally realised, and no attempt has been made hitherto to store or utilise this material, which certainly has a manurial value, especially at the present time. In September last the Board of Agriculture and Fisheries organised a series of experiments on the preservation of fruit and vegetables by drying, canning, and other methods, and preliminary experiments were made by Dr. Hamilton at Studley College, and by Mr. C. S. Martin at This work has now been deDunnington Heath. veloped, and two experimental factories are being carried on at Dunnington Heath and Broom Junction. A CATALOGUE of earthquakes felt in the Philippine Islands during 1914 has been issued by the U.S. Weather Bureau. The year was apparently uneventful, the total number of shocks recorded in the islands being 146. None of the earthquakes was of destructive strength, and only twenty-nine were of intensity above the fourth degree of the Rossi-Forel scale. As in all distinctly seismic countries, many of the disturbed areas were extremely elongated in form. The Philippine earthquakes are, however, peculiar in possessing large disturbed areas. For instance, the average area disturbed by earthquakes of intensity 4 is 9660 square miles. In Great Britain, the corresponding figure is 260 square miles.

THE refined methods of modern seismology are well exemplified in a paper by Prince Galitzin, presented to the Paris Academy of Sciences on June 21 (Comptes rendus, vol. clx., p. 810), dealing with the earthquake widely recorded on February 18, 1911. This disturbance has been prevented from falling into oblivion by the fact that the survey work of a Russian officer has brought to light the simultaneous occurrence of a cataclysmic land slide at Sarez, a situation well within the area of the epicentre as determined from the records obtained at Tashkent, Tiflis, and Pulkowa. It is easy to calculate the energy (E) liberated in this catastrophe from estimates of the weight of the disrupted mountain and the average vertical fall, whence in c.g.s. units E=2·1 to 6·0 × 10a3 ergs. Prince Galitzin next determines the energy by means of the Pulkowa seismographic records, and obtains finally E=4.3 × 1023 ergs. The two values are of precisely the same order of magnitude; hence the conclusion is drawn that the landslip at Sarez was the cause, and not the effect, of the earthquake of February 18, 1911, which thus presents a unique case where the energy liberated at the epicentre, here identical with hypocentre, is known.

THE Department of Agriculture and Technical Instruction for Ireland has reissued the explanatory memoir of the Geological Survey of Ireland, illustrating parts of the counties of Armagh, Fermanagh, and Monaghan (H.M. Stationery Office, Dublin, 1914; pp. i-iv+26; coloured map; price 3d.), The memoir describes the country around the town of Monaghan, one-inch map sheet 58. The issue of a larger and cheaper edition has provided an opportunity to add a chapter on the relation of the soils to agriculture in the district, and to describe the drumlins,

here so well developed.

The provision of a smallscale coloured map of the "solid" geology marks an important advance on the earlier edition. Plate ii., which should face p. 16, is absent from the copy we have examined.

THE report of the Fernley Observatory at Southport for the year 1914, prepared by Mr. Joseph Baxendell, meteorologist to the Southport Corporation, gives results of considerable interest. The observations have been systematically continued for the last forty-three years, and the values give a good average for intercomparison. A table is given showing the diurnal variation of the winds from different directions for the whole year, based on the observations of fifteen years to 1913, and a diagram shows the summer wind-direction frequencies for the same period. The great prevalence in summer of sea winds, from west and northwest, is well indicated, and there is a much greater prevalence of these winds in the day than in the night. Detailed tables of the several meteorological elements are given for 1914. The warmest month was August, with a mean temperature of 60.6°, which, however, is only 0.7 warmer than July, while the coldest month is January, with the mean temperature 39.9°. The temperature during the year ranged from 80° to 22°. The rainfall for the year was 32-02 in., and the wettest months were July and December, the percentage of the average being respectively 159 and 165. The brightest month was June, with 234 hours' sunshine, whilst April and August were very nearly as bright.

VOL. XXXV., part i., 1913, of the Annals of the Royal Central Office of Meteorology and Geodynamics of Rome contains a long memoir by Prof. Palazzo describing magnetic observations which he took during June, July, and August of 1913 in the Italian colony of Eritrea bordering on the Red Sea. The principal instruments employed were a magnetometer and dip circle by Dover. Observations were taken at sixteen stations situated between 14° 47′ N. and 15° 47′ N. One of the stations was on an island in the Red Sea, the others on the mainland, mostly at considerable heights, in one case 2410 metres above sea-level. The results are summarised on p. 75. A chart at the end shows the stations, and includes isogonals for 1° 30' to 1° 50′ W., isoclinals from 11° o' to 13° o' N., and lines of equal horizontal intensity. The isoclinals are nearly parallels of latitude. On p. 89 there is a record of results by other observers in Eritrea. At Massaua (Massowah), on the Red Sea, there were in all results from eight observers, including Prof. Palazzo, the earliest going back to 1839. Conclusions are drawn from these as to the secular change. A summary of the results also appears in a short paper by Prof. Palazzo in the Rendiconti Accademia dei Lincei, January, 1915.

THE July number of the Journal of the Röntgen Society contains the paper which Mr. F. Harrison Glew read before the Society in April, describing a new mechanical effect of the a rays from radio-active bodies. Mr. Glew finds that if a very thin strip of mica has one side exposed to a rays for a week or two the strip is bent, the side exposed to the rays

becoming convex and displaying iridescent colours. In one experiment a strip 2 mm. by 11 mm. and o'o mm. thick was exposed for a month to the a rays coming from a mica-covered capsule containing two milligrams of mesothorium. The strip was supported at one end so as to be 3 mm. above the cover of the capsule. It was found to have acquired a curvature equal to that of a circle of radius 48 mm. and required a weight of 460 milligrams applied to its middle point to straighten it. When reading his paper Mr. Glew suggested that the a particles arrested by the mica existed as occluded helium in the strip, an opinion which has since been verified by Mr. J. H. Gardiner, who on heating a strip in vacuo obtained the helium spectrum.

THE U.S. Department of Commerce has published a second edition of Circular No. 20 of the Bureau of Standards. The circular presents briefly, in its first section, the principles underlying the construction and operation of commercial electrical measuring instruments. This is followed by a particularly useful section on the performance of such instruments; the subjects discussed include accuracy, sensitivity, reliability, the effects of temperature change, temperaturecoefficients, the effects of stray magnetic and electrostatic fields, the effects of imperfect elasticity of springs and of friction, and the construction of scales. The information on the temperature-coefficients of voltmeters and ammeters is very useful, and methods are suggested for compensating for ordinary temperature changes. The last section contains valuable hints on the testing of instruments; it discusses in detail the application of the potentiometer to the measurement of voltage and current. Owing to its smaller temperature-coefficient, the Weston portable cell of the unsaturated type is recommended as being preferable to the Weston normal cell, in which saturated solution is used. The circular may be obtained from the Superintendent of Documents, Government Printing Office, Washington, D.C.

THE valuable reports and other publications issued by the British Fire Prevention Committee have frequently been referred to in these columns. The war emergency work accomplished by the committee during the past twelve months has been of a very extensive character, and is a remarkable example of what can be done entirely gratuitously by voluntary workers. The following are special features of the work dealt with by the committee during the first year of the war :-Fire Survey Force: At the outbreak of war, the committee formed a special Fire Survey Force of 100 surveyors to undertake at short notice any fire surveys required by the Government in an honorary capacity. Above 900 establishments taken over for war emergency work all over the country were surveyed by this force, with a total of more than 40,000 beds. Latterly re-surveys are made in cases of special fire risk. Fire Warnings: The warning service embraced the preparation and free issue of a large number of public "fire warnings" in connection with the war emergency, disseminated by the committee in the form of posters, circular letters, or as notices reproduced by the Press, etc. The total issue of posters and like publications exceeds 200,000. Fire

Service Force: The Special Fire Service Force, organised by the committee at the outbreak of the war, and comprising ex-fire brigade officers and firemen, was originally brought into such a form as to make 300 firemen readily available for mobilisation in sections within forty-eight hours. The results of the work of the committee have been far-reaching. The great care taken by the public on simple, sensible, and inexpensive lines to prevent outbreaks of fires and to meet them with organised self-help is extraordinary,

and must affect the reduction of the fire loss after the war, as it has during the war.

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A COPY of the thirteenth half-yearly volume of the Journal of the Institute of Metals has been received. For the most part the volume is a record of the papers read at the recent London meeting of the institute, to many of which attention has been directed already in these columns. In addition, there is an important contribution on "Bronzing Processes Suitable for Brass and Copper," by Mr. T. J. Baker, read on January 26 last at the Birmingham section of the institute. The part of the book containing abstracts of foreign scientific papers dealing with copper, brass, and other non-ferrous metals is remarkably complete in view of the difficulty of obtaining access to Continental periodicals. The volume contains 471 pages, ten full-page plates, and numerous illustrations in the text. It is issued under the editorship of Mr. G. Shaw Scott, and published by the Institute of Metals, Caxton House, Westminster, S.W., from whom, or through any booksellers, copies can be obtained, price 21s. net. THE Cambridge University Press has in the press, 'The in the "Cambridge Travel Books" series, Earliest Voyages round the World, 1519-1617," and in the Cambridge Public Health" series "The Spread of Tuberculosis," by Dr. L. Cobbett. The following books in the latter series are in preparation :-'Ticks as Carriers of Disease," Prof. G. H. F. Nuttall; "Serum Diagnoses," Dr. C. Browning; "Tropical Hygiene," W. J. R. Simpson; "The Purification of Water in Sedimentation, Filtration and Precipitation," Dr. A. C. Houston; "The Purification of Water by Ozone and Chlorine, and Domestic Filters," Prof. G. Sims Woodhead; "The Principles and Practice of the Dilution Method of Sewage Disposal," Dr. W. E. Adeney; “Disinfection,” Dr. C. W. Ponder; Housing in Relation to Public Health," Dr. C. J. Coleman; "School Hygiene," Dr. E. T. Roberts; "Soils, Subsoils, and Climate in Relation to Health," G. Walker; Offensive and Harmful Trades," Sir T. Oliver; 'Meat Inspection," Dr. W. J. Howarth and T. D. Young; "Vital Statistics," R. Dudfield and G. U. Yule; Foods, Sound and Unsound," Dr. H. C. Haslam.

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AN ASSOCIATION FOR THE OBSERVATION OF MARS.During the past opposition of Mars, Prof. W. H. Pickering issued a series of monthly reports dealing with the planet; these were first published in Popular Astronomy, then reprinted, and distributed in pamphlet form; in this way a system of co-operation by corre

spondence was established. This proved so mutually advantageous that Prof. Pickering is now attempting to organise an association to operate during the coming opposition of next February. Details are given in a circular letter distributed with Mars Report No. 9. The particular advantage to be derived from collaboration is continuity of record, which can only be secured in this case by having observers uniformly distributed in terrestrial longitude in consequence of

the small difference between the Martian and terrestrial days. Weekly drawings, reduced micrometric observations, if possible, and a monthly report are desired from each observer. Regular observation should begin next January, but observations of Syrtis Major in October, November, and December would be of exceptional interest.

THE POLE EFFECT IN THE IRON ARC.-Some results of further investigations carried on by Dr. St. John and Mr. Babcock, at the Mount Wilson Solar Observatory, in continuation of their important work on the minute differences of wave-length of lines in the spectrum of the iron arc when sources near the middle and near the negative pole are compared, have been communicated to the National Academy of Sciences, U.S.A. (Proc., vol. i., p. 295, 1915). It has been found that the wave-lengths of these sensitive lines are not affected by wide variations of density of the radiating vapour; change of temperature in the electric furnace does not affect the wave-lengths; with the enclosed arc the effect does not occur at pressures below 10 cm. of mercury; and, unlike the pressure shift, the pole effect does not appear to vary with wave-length. As the pole effect may amount to upwards of 0.02A, it is obviously important that it should be taken into consideration in re-determination of wave-lengths in international units. In order to eliminate the effect, the light should be taken from a point more than 2 mm. distant from the pole.

THE HARVARD OBSERVATORY.-Anything concerning this famous institution cannot fail to be of interest, and thus we welcome a reprint from the Harvard Alumni Bulletin, March 10, 1915, of two articles, one by the director, Prof. Pickering, and the other over the initials "J. D. M.," dealing with the observatory and its work respectively. Founded in 1840 by W. C. Bond, with the help of thirty subscriptions of 201. each, the endowments now amount to 200,000l., and the annual income exceeds 10,000l., yet, we are told, "there has never been a time. . when funds were needed more than they are to-day." In addition to the well-known Arequipa Station in Peru, where the 24-in. photographic doublet has been mounted, a station in Jamaica has recently been founded for visual work. No fewer than seventy complete quarto volumes of Annals have been published and eight others are in preparation, whilst about 200 circulars have been issued. Concerning the progress of the Draper Catalogue, we are informed that down to March 1, 1915, Miss Cannon had classified no fewer than 188,350 stellar spectra.

ANNUAL REVIEW OF ASTRONOMY (1914).-M. P. Puiseux has contributed to the Revue générale des Sciences of July 15 another of the useful annual reviews we have learned to expect from his pen. In referring our readers to this article, attention may be especially directed to the reference under the heading "Comets" to Innes's cosmological hypothesis and the objection he raises that it leaves unexplained the fact of the small eccentricities and inclinations of the planets and satellites. In the section on nebulæ prominence is, of course, given to the application of

interferential methods to the study of the spectrum of the Orion nebula by Fabry, Buisson, and Bourget, work which, among many other interesting results, revealed the existence of the element of atomic weight 3, previously predicted on theoretical grounds by Prof. Nicholson.



N the latest number (vol. x., No. 4) of the Journal of the Marine Biological Association there are two papers of very considerable interest. Of these, the first deals with experiments in the rearing of plankton animals (Crustacean larvæ and Copepoda) which are of importance as a food supply for fish. The author is Mr. L. R. Crawshay. Plymouth Marine Station is justly celebrated for the invention by its director, Dr. Allen, of the method of rearing various types of marine larvæ by feeding them with pure cultures of the diatom Nitzschia. By this method the larvæ of Echinodermata, Mollusca, and Annelida have been reared until they attained the adult condition. Mr. Crawshay has endeavoured to extend the method to Crustacea. He has made some interesting discoveries. Thus he finds that in spite of sterilised water and abundant food, Copepoda live a very short time unless the culture flask be kept cool and the temperature remains constant. Then he finds that the harmful action of bacteria has been much exaggerated. There are only one or two varieties which are fatal to Copepoda, but these are of infrequent occurrence. When he had arranged for a good food supply and a constant temperature, he was able to keep the delicate pelagic form, Calanus finmarchicus, alive for months, and to rear the nauplii of Pseudocalanus through all stages of development until the attainment of the adult condition. When this method has been perfected it will be possible to study the life-histories of the economically important Copepoda in detail in the laboratory, instead of, as now, piecing the development together from scattered observations of plankton.


The second paper to which we wish to direct attention deals with twin larvæ of the starfish Luidia. These larvæ developed from eggs which were at artificially fertilised mouth. When the eggs had attained the blastula stage they were sent in sea-water in a thermos flask to the author, Dr. Gemmill, lecturer in embryology in the University of Glasgow, by whom they were reared further. Dr. Gemmill ascribes the formation of twins to the shaking which the blastulæ endured on the journey from Plymouth to Glasgow; this seems to have caused partial rupture of the blastulæ at a time when the tissues are equipotential, and the partially separated fragments have each striven to produce a perfect larva.


Besides these papers the volume contains valuable list of the Annelida found in the neighbourhood of Plymouth by Dr. Allen. There is also a paper by Miss Olwen Rees, which we hope is the first of a series, which records the results of a systematic investigation of the internal anatomy of the British members of the Actinozoon family Sagartida. Too often accounts of the internal anatomy characteristic of a group have been founded on the dissection of a single "type to the structure of which the other members have been assumed to conform.

At a time when the war threatens the continued existence of such celebrated stations as Naples and Trieste. it is important to be reminded of the asset which British zoology possesses in the Plymouth Station, and of the necessity of making every effort to sustain it during this arduous time. E. W. M.


THE Ceylon Department of Agriculture has issued

a number of circulars on the tapping of individual and groups of Hevea trees and the effect of such operations on the storage of plant food. All the experiments and observations are based on Hevea brasiliensis, most of the trees dealt with being of considerable age. The papers are by Mr. T. Petch (mycologist) and by Mr. L. E. Campbell (rubber research chemist).

The first circular gives the results obtained by tapping one old Hevea tree for four years and nine months. The tree was planted in 1877, and is surrounded with other trees of the same species. It is a tree of an unusual type in so far that the main stem branches into two at about 10 ft. from the ground. In a way it is a famous specimen, and has been much photographed in past years. In four years nine months this tree has given 392 lb. 7 oz. of dry rubber: a most phenomenal crop. The rubber was obtained from the original and renewed bark on the basal portion of the stem.

The other circulars dealing with Hevea tapping results cover two distinct periods; first from 1911 to 1913 and second 1914. Experiments were made to determine the yield obtained by different frequencies of tapping and by different systems. Pricking and paring knives were also experimented with. The account of experiments for the period 1911-13 is largely statistical, very few deductions being drawn from the tabulated statements. The account of results for 1914 forms a continuation of those already referred to. While it would be too early to draw trustworthy practical conclusions from the results obtained, there are one or two points which become evident to the reader. They confirm previous results in so far that the yield per tapping increases as the time interval between consecutive operations is increased. The yield, however, in a given time is greatest with the more frequent tapping. It is further suggested that prolonged tapping on a single section, when cuts are 2 ft. apart, has a detrimental effect on the yield. Reference is made to the fact now generally recognised that results of tapping experiments hitherto conducted are of little value because no count was taken of the varying capabilities of different tappers who do the work. In the circulars we now review this cause of variation was allowed for.

Mr. Campbell's circular on the effect of tapping on the storage of plant food in Hevea brasiliensis is exceptional in character. In tapping operations the living cortex of the tree is cut away in order that the latex may freely exude. This destruction of living tissue is made good by rapid cambium activity which soon results in the production of a thick renewed cortex, except in those cases where the tappers have damaged the cambium. The renewed bark is conceived to be formed largely at the expense of reserve foods in the plant. Mr. Campbell has selected the starch grains as a reserve food, the fluctuation in quantity of which might indicate the varying effects of tapping operations. The author made a study of the bark of tapped areas, and by an ingenious method determined the number of starch grains in a given area. The work indicates that the effect of careful tapping is localised. This is not in accordance with the general view on the subject. The local effects are especially apparent in a horizontal direction, and the author suggests that by changing tapping from one part of the tree to another at intervals the resting period of each area so tapped is nearly as effective as if the whole tree were rested. The "change over" system is becoming quite common on a number of Ceylon estates. H. W.

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