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one may suspect the contrary, there may have been a scorpion in Carboniferous times with the appendages segmented as shown in the figure of Isobuthus kralupensis (p. 71); or another with an additional sternal plate between the normal second and third of the opisthosoma, as in the restoration of Microlabis sternbergi (p. 69). Most of the specimens are in continental museums; but it so happens that there is in the British Museum a fossil scorpion which Fritsch figures and describes in the present work as Eobuthus rakovnicensis. To one acquainted with recent scorpions, it is obvious that this fossil resembles them in all essential points. Yet Fritsch's restoration represents an animal differing from all known forms in characters falling so wide of one's experience that it is impossible to estimate their systematic value. If this be taken as a test case, it supplies convincing proof of the untrustworthiness of the drawings and diagnoses in the book; for it shows that the author's anatomical knowledge is too superficial to enable him to distinguish between fortuitous fractures and intersegmental joints in the fossil examples.

Haase's classification of the Carboniferous Arachnida is followed tolerably closely. To the Araneæ (spiders), however, is added the new suborder Pleuraraneæ; but its genera seem to be nothing but Anthracomarti. Promygale, for instance, differs from Anthracomartus only in the alleged presence of abdominal appendages. The evidence, however, for the existence of these seems to be of the slenderest kind. In the Opiliones figures the new genus Dinopilio, which presumably should be classified under the Araneæ, perhaps near the Arthrolycosidæ.

The volume nevertheless contains some valuable work, in addition to its usefulness as a catalogue and bibliographical record. The discovery that in the Carboniferous scorpions the lateral eyes are in advance of the medians, as in recent species, disposes of Thorell's classification of these animals into Anthracoscorpii and Neoscorpii. The author is also to be congratulated upon showing that the structure from which Cyclophthalmus took its name is a half-circle, not of ocelli, but of granules.

It is impossible not to regret the necessity for giving an unfavourable notice of a volume which has cost its author much time and trouble; but since his high reputation as a palæontologist and the style of the illustrations are likely to deceive the uninitiated into regarding this treatise as an epoch-making monograph, it would be unfair to do otherwise than utter a note of warning against putting reliance in its contents to those not in a position to judge of its merits for themselves. R. I. POCOCK.

THE CITIZEN AND THE STATE. The Citizen, a Study of the Individual and the Government. By Nathaniel Southgate Shaler. Pp. viii+339. (London: A. Constable and Co., Ltd., 1905.) Price 5s. net.

PROF. SHALER, who is professor of geology at

Harvard, has set before himself the practical and unambitious task of instructing the youth of the

United States in the first principles of citizenship. In this he has succeeded; his work is interesting, suggestive, and extremely sensible. Not being written for the specialist, it is hardly to be called profound; and the theoretical considerations which are brought forward are of the simplest. But the author's sound common sense generally carries the reader with it. A favourable specimen of his mode of argument may be found in the discussion of woman's suffrage There is no reference to the various views held by thinkers from Plato downwards; but probably Prof. Shaler's one-page argument is quite sufficient, that women, owing to their usually secluded lives, are not fitted in the same way as men to form judgments on political questions, but that, after all, if a majority of women should desire to vote, it would probably be best to give them the franchise, for the reason that it is most undesirable to have any considerable body of the people in a discontented state.

Only a few of the topics discussed in this book can be referred to here. Prof. Shaler takes the moderate view that it is more profitable to the commonwealth to engage the interest of a hundred thousand wellinformed men in politics than to have a hundred able statesmen created for public affairs. He depreciates the importance of oratory for the statesman in the present condition of American society, regards a sound head for business and a faculty for clear statement as much more valuable, and contends that the most successful statesmen in America are not (as in England) gentlemen of independent means, but lawyers and business men, whose training has taught them how to enter into associations with other men, to limit themselves to practical aims, and to form the schemes necessary for their realisation.

Naturally, in a work proceeding from the United States, one looks for, and finds, the glorification of the ideals and great men of that country; the contrast drawn between Washington and Napoleon; the contention that the War of Independence broke out because the American colonists had outgrown the system of the mother country; the distinction, too, which is drawn between the soldier and the citizen spirit. Prof. Shaler sees clearly, and discusses with impar tiality, some of the most pressing difficulties of American politics. Not much is said about trusts and tariffs, and the currency is dealt with briefly. But immigration, foreign possessions, and the negro question are quite adequately treated. Prof. Shaler laments, of course, that the streams of immigrants no longer come from the most healthy strata of society in Europe; and, in addition to criminals, paupers, and other defective persons, he would exclude those who are not able to read and write in the English language or their own. He gives no support to the view that the mere profession of the doctrines e Anarchism should be followed by condign punistment. He sees no necessity for any attempt to etend the possessions of the United States beyond the "Lynch law" he holds in detestation, and cals upon young America, on the occasions of any o bursts, however natural, of the lawless desire for ver geance, to put itself under the orders of the sherif


and even to fire on the riotous crowd. As for the negroes, whom the United States have always with them, he suggests only the need for training in the simpler arts and handicrafts; for a literary education, in his judgment, they are still wholly unfit.

PRACTICAL ORGANIC CHEMISTRY. A Systematic Course of Practical Organic Chemistry. By Lionel Guy Radcliffe, with the assistance of Frank Sturdy Sinnatt. Pp. xi+264. (London : Longmans, Green and Co., 1905.) Price 4s. 6d.


HIS book is intended mainly for students of elementary organic chemistry. The students are supposed to work about five hours per week, and, consequently, experiments which take a longer time, and must be finished without interruption, are omitted.

The exercises include a variety of important reactions and involve work with many of the more common compounds and reagents in organic chemistry. There is a set of exercises on the fatty compounds, and another on benzene; these include instructions in the observation of melting point and boiling point, in the determination of specific gravity, of the equivalent of an acid, and of sugar by the use of Fehling's solution.

This course worked through, there is a higher course, including the preparation of such substances as anisol, benzyl chloride, and benzaldehyde, the determination of equivalents and molecular weights, and of carbon, hydrogen, nitrogen, &c.

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The instructions for experiments are fairly detailed and generally good. Certain mistakes have been made. The student is repeatedly directed, after having dried a preparation by calcium chloride, to distil it in presence of the drying agent (e.g. pp. 54, 176). If a dry distillate is desired, the distillation should be carried out after removing the calcium chloride. Again, in determining molecular weight by Victor Meyer's method, the volume and temperature of the expelled gas may surely be read without waiting so long as an hour (p. 120). Is a minute not long enough?

Under protest, the authors give a section on the qualitative analysis of organic mixtures, "for the sake of students who are taking certain examinations." The authors are quite sensible of the fact that the analysis of such mixtures cannot be regarded as useful practical organic chemistry " (p. 172). Surely this is an impatient verdict. Qualitative analysis is a valuable training in so far as the student is led to bring book knowledge to bear on work in the laboratory, and is prevented from taking suspicion for proof. The teacher should re

quire him, in every case, to produce a specimen (or a derivative) of each constituent of the mixture. With this stipulation, knowledge, resource and judgment are needed in organic qualitative analysis even more than in inorganic. How many different ways are available for the separation of organic substances from one another :-precipitation, the use of different solvents, ordinary and steam distillation, extraction by ether from acid and alkaline solution, hydrolysis, oxidation, &c.! Surely time spent in mastering these methods of analysis is not wasted.


A. N. M.

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THIS is the fifth of a series of scientific monographs published under the general heading Die Wissenschaft. It consists of an historical sketch of the development of physical measurements, especially of those connected with electrotechnics. It must be admitted that in this go-ahead age the technical man finds little time to make a retrospect of his subject; he is too much concerned with its developed aspect. Even in colleges and schools, as the publisher states, the historical side of the subject is too much neglected. The present volume is intended to remove this reproach.

To give an idea of the book, we will outline here the first chapter (on current measurement). In its first section it deals with the first galvanometer, starting with the work of Oersted and Schweigger on the action of a current on a magnetic needle. Then follow the fundamental laws of constant currents as developed by Ohm, Ampère, Biot-Savart, and the methods of demonstrating them. The astatic needles of Nobili and Davy and the measurements of Faraday are next described, and this section concludes with the methods devised for calibrating the early types of galvanometer.

The second section is called the mirror galvanometer. It describes the work of Gauss and Weber on absolute measurements, the first telegraph of Gauss and Weber (1833), and the Atlantic cable furnished with mirror galvanometers by Lord Kelvin (1858). The remainder of the section deals with improvements effected in the control of the moving system (damping, &c.), and describes the galvanometers of Wiedemann, Siemens, and Kelvin, and the more recent variants of du Bois and Rubens, Paschen, Hartman and Braun, d'Arsonval, Edelmann, and Siemens and Halske.

When it is mentioned that all this is included in thirty pages it will be realised that the descriptions are exceedingly brief. The general impression conveyed is that for a book of this kind to be of much use, fuller treatment is necessary. Still, it will serve to direct attention to the general trend of advance, and to indicate the names of those that share the chief honour of it. Its value would be

considerably increased by a larger number of references to original sources of information. These are given sometimes only.

Zoologischer Jahresbericht für 1904. Edited by Prof. P. Mayer. (Berlin: Friedländer and Son, 1905.) bulky volume, like its predecessors, is published, is THE Zoological station at Naples, for which this to be congratulated on the early date of its issue and the thoroughness with which the various contributors

have done their work. In issuing a register of zoological work for 1904 so early as September of the present year, the editor and publisher have indeed beaten our own "Zoological Record"; but it must be remembered that in the present volume is included a considerable amount of literature belonging to earlier years, while it is difficult to believe that the whole of the papers for 1904 can be included.

It might be imagined, for those not conversant with the two works, that the "Zoologischer Jahresbericht" is a serious rival to the "Zoological Record," and that the publication of the one renders that of the other superfluous. As a matter of fact, this is not the case; for, in the first place, it is highly desirable that a record of zoological literature should be published in English, and, in the second, the two publications do not cover the same ground.

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[The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertaki 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.]

A Magnetic Survey of Japan.

IN NATURE of April 20 (vol. xxi. p. 578), Prof. A. Schuster has given a comprehensive review of the magnetic survey of Japan with a friendly criticism. The responsifor the bility of its writer may be a sufficient excuse following remarks partly in way of reply.

Prof. Schuster directs attention to the small space gaven to the description of the working of the instruments. The

Zoological Record," for instance, is specially devoted to the systematic aspect of the subject, particular pains being taken to include the names of all new species and subspecies. In the Continental work, on the other hand, systematic work is rigorously excluded, and attention concentrated on the bionomical, anatomical, and physiological aspects of the subject. The two records are therefore to a considerable extent supplemental and complementary to one another, more especially as in the one before us a somewhat full précis of the main subjects of the more important papers forms an important feature. The practice of including all the papers on Vertebrata under a single heading does not, indeed, appeal to us; but then, it is true, this is in some degree compensated by dividing the summary of their contents into their respective class-positions. So far as we have been able to judge, the quotations of the titles of the papers and the references to their places of publication are singularly free from error, and the volume, like its predecessors, cannot fail to be of the highest value to all workers in morphological and anatomical zoology. R. L.

Examples in Arithmetic. By C. O. Tuckey. Pp. xii +241 + xxxix. (London: George Bell and Sons, 1905.) Price 38.

The Primary Arithmetic. Parts i. and ii.. Edited by Dr. Wm. Briggs. Pp. 80 and 94. (London: The University Tutorial Press.) Price 6d. each. THESE books are intended for the use of teachers who instruct their classes orally in the processes and rules of arithmetic, and who only require the assistance of graduated sets of exercises. In the work by Mr. Tuckey the course is fairly complete, embracing the usual commercial arithmetic, with a chapter on the application of proportion to problems in geometry and physics, and a section devoted to numerical computations by the aid of compound interest, logarithmic and trigonometrical tables, in which a little elementary trigonometry is introduced. There are examples on graphs and squared paper work, and the users of the book will have an abundant choice of exercises of modern type.

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The Primary Arithmetic " will be complete in three parts. The first part gives sets of exercises on the four simple rules and on the compound rules for money. The examples increase in difficulty by almost imperceptible stages, beginning with those of the simplest kind, and they are suitable for very young scholars. Part ii. completes the compound rules for weights and measures, including the metric system. Then follow exercises on vulgar fractions and on practice and invoices. In these two parts, as well as in the book by Mr. Tuckey, the answers to the exercises occupy a considerable space at the end of each volume.


arises from the fact that these instruments were essentially the same as the one used in the previous survey of 1887. and described in vol. ii., pp. 178-193, of the Journal of the College of Science, Imperial University, Tokyo to which the reader is referred for details. A few improvements that have since been made are mentioned in the present report, pp. 7-8.

We are glad to see that the methods adopted for calculating the corrections for heights of stations and the way of disposing with the vertical current met his approval only Prof. Schuster seems to attribute these currents they are as much, if not more, due to the inadequacy ut uncertainties in the observations, whereas we infer that

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the empirical formulæ, from the fact that they vanish near the middle of the several countries treated (p. 125)

Perhaps the more important point is with regard to the question of the seat of action. To avoid confusion, it might be well to remark that the word potential is used in different senses by different writers; some use it to denote a function which satisfies the Laplacian equation

V=0, and others to denote the line integral of an irrotationally distributed vector, whether the solenoidal condition be satisfied or not. It is in the latter general sense that the word is used in the report.

Now Gauss's method of separating internal and external sources of action is based upon the assumption that the se sources are entirely separated from each other by a free space; in other words, the Laplacian equation holds strictly over a finite portion of the space surrounding the earth surface. This is very plausible when we consider the earth as a magnetised body, as appears a posteriori. But when we abandon the restriction of the solenoidal distribution the method is no more applicable, and the observation of force over a spherical surface is not sufficient to settle the seat of action, although it may be expansible in harmonse form if its distribution is continuous, so that the Gaussian expansion must be taken in "Gauss's sense" (end af first paragraph, p. 140 of the report).

The possibility of the distribution of magnetism in the space surrounding the earth surface might appear quite extravagant, and may be included amongst what Gauss calls boldenlose Phantasien," so long as we are sidering the main causes of the terrestrial magnetism; but when we come to discuss the external causes and the horizontal atmospheric current the effects of which amount assumption of the distribution being thoroughly solenoidal to only a small fraction of the observed forces, nur would seem subject to doubt, or at least to require observational evidence, so that strictly speaking, the mode of distribution must remain perfectly arbitrary so long a we adhere solely to the observed elements" of magnetic forces on a spherical surface, when no further assumption than the Newtonian law of action is admitted.

It may not be unnecessary to add here that the search for the seat of action from observations of force over a surface is an inverse problem, and includes any arbitrary distribution of magnetism the resultant effect of which vanishes on that particular surface; we can put any syste of magnets or electric circuits outside the surface, provided we envelop that surface with a counteracting heal or shells over which a proper distribution of magnetism is made according to Green's method of finding the density of induced electricity on a conductor, besides ans

amount of closed magnetic shells and solenoids. It will
thus be seen that even if we take the internal and external
sources to be detached, the plain proposition given by
Prof. Schuster would appear to require a modifying clause
in order to be exact.

Physical Laboratory, Imperial University, Tokyo,

A Polarisation Pattern.

THE following may be of interest to some of your readers. A cylindrical mica chimney of an Auer gas-light is placed vertically on a varnished table. If we look through it at the diffused daylight from a window reflected by the table, faint coloured bands are seen running parallel to the length of the cylinder near both edges. If observed through a Nicol's prism, the band appears very beautiful.

T. TERADA. Physical Laboratory, Science College, Imperial University, Tokyo, September 8.

A Focusing Screen for Use in Photographing UltraViolet Spectra.

THE sensitive surface upon which Stokes projected the ultra-violet rays when observing metallic lines and absorption spectra consisted of a plate of plaster of Paris moistened with a paste of uranium phosphate acidified with phosphoric acid (Journ. Chem. Soc., vol. xvii., 1864). Soret used uranium glass and solutions of fluorescent substances such as æsculine in liquid cells. I have found that the most convenient and effective screen for examining spectra with a quartz spectrograph is one such as is used for the X-rays. It may be made as follows:-a photographic plate is first cleared silver bromide by fixing and washing, and when the film is partly dry, but the gelatin still soft, it is dusted over with a powder of barium platinocyanide crystals, so as to be somewhat thickly coated with the salt. This is fixed in the dark slide of the camera. To focus a spectrum, the slide is tilted to the necessary angle, and a somewhat powerful focusing glass with a flat field is applied to the uncoated surface of the plate, when both the visible and ultra-violet spark spectra may be plainly seen by transmission, the latter by reason of the fluorescence excited. The focusing glass should be first carefully adjusted for any visible object on the other side of a plain glass plate, such as a fine hair fastened upon it, and the position of the eyepiece is then fixed. Suitable focusing glasses are those made by Dallmeyer and by Taylor, Taylor, and Hobson. When the spectrograph has been adjusted by means of the screen, the ultra-violet lines appear quite as sharp as those in the red and yellow, even the details in the group of cadmium lines between wave-lengths 2100 and 2400 are well defined, and a very fair photograph may be obtained; but for the most accurate focusing photography must be resorted to. W. N. HARTLEY.

Royal College of Science, Dublin, October 2.

The Omission of Titles of Addresses on Scientific Subjects.

THE published reports of the British Association make an omission of an equal and opposite character to that about which your correspondent complains. Perhaps these are intended to cancel out. I refer to the publication of titles only, without any text. On receiving the last report (1904, Cambridge) I analysed this matter so far as it relates to Sections A and G, in which I am most interested. In Section A there were 83 communications, 29 of which appear by title only, and of these publication elsewhere is referred to in foot-notes in 4 cases, leaving 25 to the recollection of the audiences who heard them. Section G was better. There were 25 communications, and 13 appeared by title only; but of these 9 may be traced by those who take the trouble to consult the other publications referred to in the foot-notes. A. P. TROTTER.

Westminster, October 3.



THE International Congress on Tuberculosis, held in Paris on October 2-7, has undoubtedly served as a medium for a most fruitful interchange of views by those interested in the struggle against tuberculosis. The congress was held in the Grand Palais, which from its extent enabled the members to be collected under one roof. The first day was devoted to the formal opening, when the delegates were welcomed by the President of the French Republic, who also after the close of the congress gave a reception at the Palais de l'Elysée. The chief social functions, which were characterised by complete success, comprised a reception at the Hôtel de Ville by the Municipality of Paris, an "at home" by the Figaro, at which performances were given by well known artistes, a soirée at the Hôtel Continental given by the president of the congress, Dr. Hérard, another at the Châtelet Theatre by the Matin, and a visit to Vaux de Cernay on the invitation of Dr. Henry de Rothschild.

The British Government was represented by Dr. Theodore Williams and Dr. Bulstrode, the National Association for the Prevention of Consumption by Sir William Broadbent and Dr. Perkins, while the foreign Governments and all the leading medical societies and institutions had their special official representatives.

The chief feature of the congress was reserved for the closing séance, when Prof. v. Behring announced that he had every reason to hope he had discovered a method of treating tuberculosis which would be as efficacious as the anti-toxin treatment of diphtheria he had first proposed in 1890.

His statement, received with great enthusiasm, was to the effect that, although he had made a great step, the value of his proposed procedure must be tested on animals in other laboratories than his own, and clinically by physicians with an intimate knowledge of the varieties of pulmonary tuberculosis, before it could be said that an actual curative medium had been found.

Prof. Behring, as had been anticipated, gave no exact details as to the method of obtaining or administering his latest therapeutic discovery, but the earlier stages of his work are to be explained in a forthcoming book entitled Modern Problems of Phthisiogenetic and Phthisiotherapeutic Physiology illuminated by History."

His experiments have led him definitely to abandon the idea of introducing living tubercle bacilli into the human body with a therapeutic object. He has discovered a substance, to which he has given the name T.C., which represents the vital principles of the tubercle bacillus of Koch. To the presence of this substance, which possesses extraordinary fermentative and catalytic properties, is due both the hypersensibility of living organisms to Koch's tuberculin and the This T.C. protective reaction against tuberculosis. impregnates and becomes an integral part of the cells of any organism with which it comes in contact, undergoing a metamorphosis into another substance to which the name T.X. has been given.

This elaboration of T.C. in the organism is a long and perilous process. Prof. v. Behring claims to have succeeded in producing this change in vitro by freeing the T.C. from certain substances which impair its therapeutic action. Of these he distinguishes three groups: (1) a substance (T.V.) only soluble in pure water, and possessing a fermentative and catalytic action. To the presence of this substance are due the toxic effects of Koch's tuberculin. One gram of this in the dry state is more toxic than a litre of the old

tuberculin. (2) A globulin (T.G.L.), soluble in neutral saline solutions, and also toxic. (3) Several non-toxic substances soluble only in ether, chloroform, and the like. The residue of the tubercle bacillus after the removal of the foregoing he terms the restbacillus; this still retains the form and staining reactions of the original tubercle bacillus. The restbacillus can be converted into an amorphous substance readily taken up by the lymphatic cells of animals undergoing a metamorphosis and leading coincidently to the production of oxyphil granules in these cells and of immunity to the tubercle bacillus in the organism as a whole.

Prof. v. Behring has convinced himself that this T.C. can be elaborated in vitro in a fashion which will enable it to be applied efficaciously and without danger in human therapeutics, but until this has been confirmed he does not propose to publish his full results.

The scientific interest of the congress naturally divided itself into two parts, the exhibition of pathological specimens, of models, photographs, and plans of sanatoria, instruments, sterilising machinery, and the like in the museum on the ground floor of the Grand Palais, and the actual communications made to the congress. Both presented features of great importance. Among the exhibits of more especial interest were a series of specimens indicating the results of inoculation of bovine, human, and avian tubercle in different animals, lent by the Gesundheitsamt of Berlin, and a similar series shown and thoroughly demonstrated by Dr. Lydia Rabinowitsch. The latter observer had been able to show the varying grades of virulence of the tubercle bacilli from different sources, but had not been able by transference through different animals to convert bacilli with the cultural properties of bovine bacilli into those with the cultural characters of human tubercle bacilli and vice versa, although this could not be seen from the naked-eye appearance of many of the specimens. Neither had she so far repeated Nocard's results of converting avian into human or human into avian bacilli, although she exhibited an example of a bird which had suffered, apparently spontaneously, from tuberculosis, in which the cultural appearances were those of human bacilli. Dr. Calmette, of the Pasteur Institute of Lille, showed an important series of specimens from goats and kids. Kids which had been fed on the milk from mothers the mammæ of which were infected with bovine tubercle presented caseation of the mesenteric glands and also pulmonary lesions, apparently spreading through the peribronchial glands and lymphatic chain, although the retropharyngeal chain of glands remained uninfected. In cases in which the mothers had been inoculated with human or avian tuberculosis or with the Timothy bacillus only the mesenteric glands were infected. Adult goats to which doses of a culture of bovine tubercle had been administered through an œsophageal tube always died rapidly of pulmonary tuberculosis without apparent intestinal lesions and only a few scattered points of caseation in the mesenteric glands. Nothing approaching the degree of mesenteric affection seen in kids was found. This confirms Prof. v. Behring's announcement in 1903 that pulmonary tuberculosis might result from intestinal infection without producing local lesions at the point of entry. The Alfort Veterinary College showed a series of specimens, and others were to be seen in the museum of the college, which members of the congress were invited to visit. Amongst others were examples of the comparatively rare tuberculosis of the horse, and evidences that dogs suffer severely both from pulmonary and intestinal tuberculosis. Prof. G. Petit, of Alfort, has shown that such affec

tions are steadily on the increase, and constitute an important factor in the campaign against tubercu losis, since a household otherwise protected to the best of human ability may become infected by a pet dog, which, having acquired tuberculosis in the streets or elsewhere, subsequently lies on the bed of children and licks their faces. The tuberculosis of dogs is more often open than had been anticipated; this means that tubercle bacilli would be constantly about their mouths, and so be readily transferred The most common organism is the human bacillus, and the dogs most affected are those from small cafés where the air is constantly full of dust and dried sputum.

In the hygienic section were full size models showing the ordinary hotel room with its heavy hangings and dust accumulation, and the same room as it should, and could at less cost, be properly furnished with easily disinfected materials. Another group showed the great superiority in light, air, and general hygiene of a prison cell over the attic rooms with skylights, often not opening, in which most servants in Paris are accustomed to sleep.

For the purpose of receiving communications the congress was divided into four sections, the first two dealing with medical and surgical pathology and therapeutics respectively, the third with the protection of infant life, and the fourth with the protection of the adult and social hygiene.

In many subjects the two former sections overlapped, especially in dealing with the nature and varieties of tuberculosis and the value of serotherapeutics. The general conclusions appeared to be that the morphological appearances of the different varieties of the tubercle bacillus and other acid-fast bacilli were very similar, but that cultural differences existed, and that there were wide variations in toxicity. Special reports were made on this subject by Profs. Arloing, Kossel, and Ravenel. These showed that the infection of man by bovine tubercle bacilli, which are the most virulent, could occur through feeding with the unsterilised milk of tuberculous cows. All mammals appeared to suffer from infection by both types of bacilli, but no other type of mammalian bacilli could be established from cultural or morphological characters. So far as was known, tubercle bacilli modified in virulence by passing through animals other than mammals could be ultimately traced to a human or bovine origin, and restored by passage through cultures and other animals to their original forms. While the general impression seemed to be that the tubercle bacillus is in reality but one species, it was admitted that no evidence of trans formation of the one type into the other, in cultural characters at any rate, had so far been produced, although varying grades of virulence in each type were recognised.

In a general study of acid-fast bacilli, Drs. Besançon and Philibert distinguish between true acidfast bacilli which remain so under all conditions of culture, growth, and passage through animals, and those which for a single generation have acquired acid-fast characters.

They found that many bacilli grown on appropriate media containing fats, of which lanoline was the best, acquire the power for some time of resisting decolorisation by acids or by acids and alcohol. Subcultures grown on similar fatty media are also acidfast, but subcultures on ordinary media possess no such power. To distinguish between these groups it was necessary to stain for a longer period than usual. and then to expose the films to the action of acid for many hours.

When deeply stained the tubercle bacillus will resist decolorisation for twelve to eighteen hours; the

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