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structural unit remains the cell, despite the modifications the cell necessarily undergoes as a fixed element in the various tissues and organs. All phases of animal and plant life are demonstrably of cellular origin and organisation, and their vital manifestations represent the summed-up activities of cells. Every vital problem therefore is ultimately a cellular problem, and a direct study of the cell, in so far as may be possible, is the keynote of the problem it is desired to investigate. A histological technique, aided by the microscope, will naturally be employed where it is desired to study the relations of parts and the structural organisation of the tissues and their cellular elements. The soluble products of the living cell spontaneously present themselves for examination by chemical and other means. It is otherwise with regard to the agencies acting and the processes occurring within the confines of the cell. These are naturally beyond the range of the ordinary methods of observation. The essential processes of life are intra-cellular and intimately bound up with the living substance of the cell, and of these but few data are possessed. The importance of the problems involved is as great as their investigation is difficult. The cell exercises its vital functions in virtue of a specific physical and chemical organisation of its molecular constituents. The ordinary methods of biological and chemical research modify or destroy this organisation, and do not admit of an intimate study of the normal cell constituents. For this purpose it is essential to eliminate or to reduce to a minimum the influence of external modifying agents on the cell or its immediate products. An intracellular physiology can only be based on a direct study of intra-cellular constituents apart from their secretions and products. This, under ordinary circumstances, is impossible, with respect to actively functionating and intact cells. It is obvious, therefore, that the first desideratum is a suitable method of obtaining the cell plasma for experimental purposes, and it is only recently that this has been successfully accomplished. The most feasible means of procedure appeared to be the use of mechanical agents which, whilst bringing the cell substance within the field of observation, would at the same time be least likely to affect its character and constitution. The method consists in a mechanical rupture of the cells and the release of their contents under conditions favouring the conservation of their properties. The first successful application of this description of method was made by Buchner in the particular instance of the yeast cell, and with brilliant results. The researches of Buchner were of wide biological significance, and were suggestive of much more than a cell-free alcoholic fermentation of sugars. They demonstrated the possibilities of the new methods with regard to more general vital problems. The Buchner process consisted in a mechanical trituration of the yeast cell with the aid of sand, and a subsequent filtration of the resultant mass under pressure through Kieselguhr. The filtrate contained the expressed constituents of the yeast cell which were capable of passing through Kieselguhr, and the product in virtue of its fermentative properties. was termed Zymase.'

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The writer and his colleagues have during the past four years been engaged in investigating the application of cognate methods to biological research. The advice and help generously afforded by Professor James Dewar materially forwarded the progress of the research.

It was considered that by the employment of low temperatures a disintegration of living cells might possibly be accomplished, and a wide field of inquiry opened to investigation in the biological laboratory. For this purpose the methods of mechanical trituration required refinement in several directions.

The conditions it was desired to fulfil were, a rapid disintegration of the fresh tissues and cells, an avoidance of heat and other modifying agents during the process, and an immediate manifestation of the cellular juices obtained.

It had likewise been noticed that ordinary filter pressing through Kieselguhr removed physiologically active substances from the cell juices. Liquid air appeared to be the most convenient means of obtaining the necessary cold, and it presented the advantage of a fluid freezing medium, in which the material to be manipulated could be directly immersed. The temperatare of this reagent (about 190° C.) would in addition prevent heat and chemical changes, whilst reducing the cells

to a condition of brittleness favourable to their trituration without the addition of such substances as sand and Kieselguhr, which might modify the composition of the resultant product.

The method, if successful, would meet the conditions desired for the subsequent study of the intracellular juices. It may be briefly stated that by the application of low temperatures a mechanical trituration of every variety of cell per se has been accomplished, and the fresh cell plasma obtained for the purpose of experiment. A number of control experiments have demonstrated that immersion in liquid air is not necessarily injurious to life-bacteria, for example, having survived a continuous exposure for six months to its influence. The actual trituration of the material is accomplished in a specially devised apparatus, which is kept immersed during the operation in liquid air.

The normal and diseased animal tissues have been treated in this manner, and their intracellular constituents obtained-e.g. epithelium, cancer tissues, &c.

Moulds, yeasts, and bacteria have been rapidly triturated under the same conditions and the respective cell juices submitted to examination.

The severest test of the capabilities of the method was furnished by the bacteria, an order of cells for which the standard of measurement is the mikron. The experiments proved successful in every instance tested. The typhoid bacillus, for example, is triturated in the short space of two to three hours, and the demonstration has been furnished that the typhoid organism contains within itself a toxin. From these and other researches it has become evident that there exists a distinct class of toxins and ferments which are contained and operate within the cell or bacterium, in contradistinction to the now well-known class of toxins, which are extra-cellular-i.e. extruded during life from the cell into the surrounding medium. To this latter class belongs the diphtheria toxin, which has been so successfully used in the preparation of diphtheria antitoxin. A number of infective organisms do not produce appreciable extra-cellular toxins, and the search must therefore be made within the specific cells for the missing toxins to which the intoxication of the body in the course of the disease in question is probably due. The practical utility of investigating these intracellular toxins has already become evident in the preparation from the intra-cellular toxin of the typhoid bacillus of a serum having antitoxic value as regards this toxin.

The experiments made with the pus organisms have already shown that intracellular toxins exist in this important order of disease germs. The cell juices of other types of pathogenic bacteria such as the tubercle and diphtheria bacillus present characteristics of equal interest.

The application of low temperatures has aided the investigation of certain other biological problems.

The photogenic bacteria preserve their normal luminous properties after exposure to the temperature of liquid air. The effect, however, of a trituration at the same temperature is to abolish the luminosity of the cells in question. This points to the luminosity being essentially a function of the living cell, and dependent for its production on the intact organisation of the cell.

The rabies virus has not yet been detected or isolated, although regarded as an organised entity. The seat of the unknown rabies virus is the nervous system. If the brain substance of a rabid animal be triturated for a given length of time at the temperature of liquid air, its infective properties as regards rabies are abolished. This result appears to be a further indication of the existence in rabies of an organised virus.

The method described admits of a fresh study of the question of immunity from an intra-cellular standpoint.

The intra-cellular juices of the white blood-cells have been obtained, and tested with regard to bacteriolytic properties, and the natural protection that may thus be afforded to the body against the invasions of micro-parasites.

The application of low temperatures to the study of biological problems has furnished a new and fruitful method of inquiry.

3. Report of the Committee on securing Duty-free Alcohol for Scientific Research.-See Reports, p. 170.

4. The Cause of the Lustre produced on Mercerising Cotton under Tension. By JULIUS HÜBNER, F.C.S., and WILLIAM J. POPE, F.R.S.

It is generally supposed that the production of a lustre on treating stretched cotton yarn with strong caustic soda is conditioned by only two factors-namely, by the simultaneous swelling and shrinking of the fibres. The authors show, however, that a third effect is essential to the production of any appreciable silky lustre: this consists in an uncoiling of the naturally twisted ribbon constituting the cotton-fibre.

On immersing a loose cotton-fibre in strong caustic soda on the microscope stage, it is seen to rapidly untwist, to swell, and at the same time to shorten in length; the untwisting generally continues until the natural twist has nearly completely disappeared, after which the fibre presents the appearance of a round irregularly curved rod with a comparatively smooth surface. If the fibre is fixed at one end and treated with caustic soda, it twists either to the right or to the left, according as it was originally coiled towards the left or towards the right; in the most generally occurring case, that, namely, in which the fibre is coiled partly to the right and partly to the left, the untwisting attending the treatment with soda takes place first towards the left and then towards the right, or vice versa. If the fibre is prevented from contracting by being held at the two ends in a stretched condition it still untwists when treated with soda; since, however, the whole of the untwisting does not take place simultaneously, the untwisting of one part causes another part, which has already become unwound and attained the condition of a gelatinous rod, to become tightly twisted in the opposite direction to its original twist.

The stretched fibre thus again acquires a corkscrew-like appearance, part of the twist being right- and part left-handed, with the difference, however, that whilst the raw fibre forms a twisted ribbon creased or folded at the turns, treatment with soda converts it into a rod of circular cross-section which has been twisted whilst in a gelatinous state. The twisting of the fibre under these conditions results in the production on the rounded surface of spiral ridges possessing smooth curved contours, which reflect the light at all angles of incidence and reflection just as do the coils of a polished corkscrew. The fibre, therefore, becomes lustrous.

The high degree of transparency possessed by the cotton-fibre introduces difficulties into the microscopic examination of the changes referred to above. But although the fibre is amorphous, it is doubly refracting owing to internal strain; the authors therefore find it convenient to conduct the microscopic examination of the fibre between crossed Nicol prisms, and to accentuate the difference in tint of the various parts by introducing a one-eighth wave-length retardation plate of mica between the Nicols in such a way that its principal directions make an angle. of 45° with those of the prisms. This enables the internal canal, cracks in the surface, and differences in thickness to be made out with great ease. The correctness of the explanation now given of the lustre is shown by a series of photomicrographs taken in natural colours in elliptically polarised light under the conditions just referred to. The authors have to thank their colleague, Mr. Charles W. Gamble, Director of the Photographic Department in the Manchester Municipal. School of Technology, for having assisted the work by the production of these photographs. A further confirmation of the correctness of the conclusions now arrived at is afforded by the observation that whilst cotton-fibres mercerised loose have a practically circular cross-section, fibres treated under tension with soda show cross-sections shaped like polygons with rounded corners.

An independent proof of the authors' conclusions that the untwisting of the fibre is as essential a factor in the production of the gloss as are the swelling and

the shrinking, is afforded by an examination of the action of reagents on cotton yarn. Thus, hanks of a long staple yarn having a mean breaking strength of 417421 grams were immersed loose in caustic soda (sp. gr. 1-342) and saturated barium mercuric iodide solution, and the following changes in the breaking load of the yarn and the lengths of the hanks were found to result:

Caustic Soda.-Mean breaking load, 526338 grams; shrinkage, from 66.0 to 44.8 cm.

Barium Mercuric Iodide.-Mean breaking lead, 526.6 ± 3.3 grams; shrinkage, from 66.0 to 48.9 cm.

Although the shrinkage and the increase in the breaking load brought about by these two reagents are so nearly the same, yet on immersing hanks under tension in these solutions and washing whilst still under strain the hank treated with soda acquires a brilliant lustre, whilst that treated with the iodide exhibits only a trace more lustre than the untreated yarn. The explanation of this result is found in the fact that caustic soda causes rapid untwisting of the fibre, whilst barium mercuric iodide does not cause untwisting.

The authors give a list of reagents which bring about two of the three effects shown to be essential to the production of lust re-namely, swelling, shrinking, and untwisting and find that lustreing' cannot be effected with such reagents; several solutions are known, however, which cause the three effects, and with the aid of such liquids the lustre can always be produced.

5. Stead's recent Researches as to the Causes and Prevention of
Brittleness in Steel. By Professor T. TURNER, M.Sc.

After briefly referring to the nature of a eutectic, and the characteristic microstructure of such bodies, as pointed out by Osmond, the author outlined the structure of steel. Special reference was made to the properties and distribution of ferrite and pearlite in metal, when used in its natural state for constructional purposes, and containing about 0.45 per cent. of carbon. A short summary was then given of the work of Brinell, Heyn, Stansfield, and of Stead and Richards in reference to brittleness caused by heating steel either for a short period to a high temperature, or for a longer time at a lower temperature (900° C.). The crystalline character and brittleness so produced can be at once removed, in most cases, by heating to slightly under 900° C. The structure of steel of good quality is, therefore, largely dependent on the rate of cooling through the point Ac1. Details were also given of the work of Stead and Richards on the production of sorbite in steel. The maximum quantity of sorbite is obtained by cooling the heated steel rapidly until its temperature is below the critical points, and then tempering either by external heat, or, in the case of rails and other similar large objects, by the internal heat of the partly cooled steel. Rails which have been rendered sorbitic in this way have a higher tensile strength and greater wearing power than ordinary rails. Sorbitic steel, when tested by repeated reversals of stress, also shows much greater toughness and endurance. A number of photographs were exhibited which showed very plainly that the microstructure of the sorbitic portion of a steel rail is quite different from that of the rest of the steel. The normal portion consists of a heterogeneous mixture of ferrite and pearlite, while the sorbitic portion is almost perfectly homogeneous.

The papers to which special reference was made were read at the Iron and Steel Institute, September 1903, and are as follows:

1. The Burning and Overheating of Steel, by A. Stansfield.

2. The Restoration of Dangerously Crystalline Steel by Heat Treatment, by J. E. Stead and A. W. Richards.

3. Sorbitic Steel Rails, by J. E. Stead and A. W. Richards.

6. The Colours of Iodides. By WILLIAM ACKROYD, F.I.C.

The general law of the relation of colour to chemical constitution was stated by the author in 1892. Briefly it is that in related compounds of the general formula, AB, as B increases in weight (either in atomic mass or multiple of atomic mass) there is increase of absorption of light in definite manner, so that the visible effect is progression in the metachromatic scale from the white towards the black end. With one colour vision this would appear like a gradual darkeningan aspect of the phenomenon which the author regards as being presented by X rays in the photographic effects produced by them after passing through equal thicknesses of the members of a series AB. That this generalisation is reasonably fact-embracing is seen when it is stated that there are only about 2.27 per cent. of exceptions in a survey of some 616 correlated inorganic coloured compounds, and many of these exceptions are of a doubtful nature.

Iodides conform to the law; the more heavily weighted molecules have colours nearer the black end of the scale, while the lighter ones, on the other hand, come nearer the white end. Thus in vertical series of the periodic classification arsenic triiodide is orange as compared with the red of antimony and bismuth triiodides; magnesium, zinc, and cadmium iodides are white, while mercuric iodide is yellow or red. In the periodic groups there are forty-one examples of iodides; only three are apparently unconformable, two of these being doubtful exceptions.

When there is more than one iodide of the same metal we have again conformity to rule, thus:-Hg,I, is olive green, and HgI, yellow or red.

The iodides have also a normal colour when compared with the other halides of the same radical as in the series ASF, AsCI,, AsBr, and AsI. In the tabulation of these relations conformity to the law is seen both in horizontal as well as vertical groups, and 270 colour facts are presented in such a tabulation which give less than 3 per cent. of exceptions.

Finally the result of recent research shows that the element iodine has also a normal colour among the other liquid and solid halogens; their absorption increases from fluorine to iodine through the extremes of white to black.

It is amply apparent, therefore, that in a comparable series of compounds having similar molecular structure as represented by the same general formula we may have colourless or white bodies at one end and coloured substances at the other end. Hence it is contended that Professor H. E. Armstrong's view that colour is an indication of 'quinonoid structure does not hold for iodides as maintained by Miss I. Smedley, nor for inorganic bodies generally. Tables are given illustrating these various observations.

7. On Essential Oils. By Dr. O. SILBERRAD.

The production of essential oils, although of extreme antiquity, has only recently been made the subject of scientific research. The earlier methods of extraction from the plants were exceedingly crude, and it was only in the early part of the nineteenth century that the industry received a new impulse by the introduction of steam distillation for the recovery of these essences. Chemical research has in recent years led to the replacement of the natural oils to some extent by products artificially prepared. As an instance of this, the author's recent discovery that carvone, C11O, the active principle of carraway oil, could be

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Chem. News, 1893, lxvii. 27.

2 On Opacity to the Röntgen Rays. W. Ackroyd and H. B. Knowles, Jour. Soc. Dyers and Colourists, vol. xii. April 1896.

Brit. Assoc. Report, 1902, p. 582.

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