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NEW BOOKS Forced Movements, Tropisms, and Animal Conduct. B y Jacques Loeb. X 15 cm; pp. 209. Philadelphia: J . B . Lippincotd Company, 1918. Price: &?.5o.--The titles of the chapters are: introduction; the symmetry relations of the animal body as the starting-point for the theory of animal conduct; forced movements; galvanotropism; heliotropism; an artificial heliotropic machine ; asymmetrical animals; two sources of light of different intensity; the validity of the Bunsen-Roscoe law for the heliotropic reactions of animals and plants; the effect of rapid changes in intensity of light; the relative heliotropic efficiency of light of different wave-lengths; change in the sense of heliotropism; geotropism; forced movements caused by moving retina images; stereotropism; chemotropism; thermotropism; instincts; memory image and tropisms. The following selections, pp. 7, 21, 31, 45, 66, 72, 82, 126, 131, 163, 171, give a fair idea of the book. Animal conduct is known to many through the romantic tales of popularizers, through the descriptive work of biological observers, or through the attempts of vitalists to show the inadequacy of physical laws for the explanation of life. Since none of these contributions are based upon quantitative experiments, they have led only to speculations, which are generally of an anthropomorphic or of a purely verbalistic character. It is the aim of this monograph to show that the subject of animal conduct can be treated by the quantitative methods of the physicist, and that these methods lead t o the forced movement or tropism theory of animal conduct, which was proposed by the writer thirty years ago, but which has only recently been carried to some degree of completion. “Physiologists have long been in the habit of studying not the reactions of the whole organisms but the reactions of isolated segments (the so-called reflexes). While it may be justifiable to construct the reactions of the organism as a whole from the individual reflexes, such an attempt is in reality doomed to failure, since reactions produced in an isolated element cannot be counted upon to occur when the same element is part of the whole, on account of the mutual inhibitions which the different parts of the organism produce upon each other when in organic connection; and it is, therefore, impossible to express the conduct of a whole animal as the algebraic sum of the reflexes of its isolated segments.” “E. P. Lyon has shown that if the tail in a normal shark be bent to one side (without changing the position of the head) the eyes of the animal move as promptly as compass needles in association with the bent tail around the same axis in which the bending occurs, but in an opposite sense. On the convex side of the animal, the white of the eye is more visible in front, on the concave side it is more visible behind; hence the former has moved backward, the latter forward. This was observed not only in the normal fish but also when the optic and auditory nerves were cut. The central nervous system acts as one unit. R. Magnus and his fellow-workers have shown that an alteration in the position of the head of a dog inevitably alters the tone of the muscles of the legs. These and other associations and mutual inhibitions make possible that simplification which allows us to treat the organism as a whole as a mere sym21

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metry machine, a simplification which forms the foundation of the tropism theory of animal conduct. It would, therefore, be a misconception to speak of tropisms as of reflexes, since tropisms are reactions of the organisms as a whole, while reflexes are reactions of isolated segments. Reflexes and tropisms agree, however, in one respect, inasmuch as both are obviously of a purely physico-chemical character.” “The importance of these forced movements caused by lesion of the brain for the explanation of the conduct of normal animals lies in the fact that the latter is essentially a series of forced movements. The main differences between the forced movements after brain lesion and the conduct of the normal animal lies in the fact that the former are more or less permanent; while in the normal animal conduct the changes in the relative tone of symmetrical muscles leading to a temporary forced movement are caused by a difference in the velocity of chemical reactions in symmetrical sense organs or other elements of the surface.” “All the phenomena of galvanotropism are, therefore, reduced to changes in the tension of associated muscles or contractile elements, as a consequence of which the motion of the organisms toward one pole is facilitated, while the motion toward the opposite pole is rendered difficult. Galvanotropism is, therefore, a form of forced motions produced by the galvanic current instead of by injury to the brain. “Heliotropic curvature of sessile animals can be shown equally well in a hydroid, Eudendrium. It is necessary to cut off the old polyps a t once when the animal is brought into the laboratory and to put the stem into fresh, clear sea water. In a day or two new polyps are formed by regeneration and these polyps will bend toward the light until their axis of symmetry is in the direction of the rays of light. The region a t the base of the polyps is contractile and when light strikes the polyps from one side only, the stem on the side of the light contracts more than on the other side, and this results in a bending of the stem, whereby the polyp is put into the direction of the rays of light. As soon as the axis of the polyp is in the direction of the rays of light (provided there is only one source of light), the tension of the contractile elements is the same all around, and there is no more reason for the organism to change its orientation. It, therefore, remains in this orientation to the light. “The muscle tension theory of animal heliotropism is, therefore, proved for all classes of the animal kingdom, infusorians, hydroids, annelids, crustaceans, etc. It would be wrong to state that the theory holds only for insects.” “Garry has shown that when a fly with one eye blackened is put on a vertical stick, it still walks upward, but in spirals around the stick, instead of in a straight line. The asymmetry of locomotion changes only the geometrical nature of the path in which the animal moves, from a straight line to a spiral, but does not alter the forced movement character of the reaction. Bancroft has pointed out that when in a positively heliotropic amphipod one eye is blackened and the legs of the same side are cut off, the animal’s path would be a combination of a circus motion induced by the blackening of the eye and of a rolling motion around its longitudinal axis. Both effects combined would result in the animal swimming ih a spiral path, and if the animal is positively heliotropic it would swim in such a path toward the light. This is the path

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which aquatic, asymmetrical positively heliotropic organisms, such as the flagellate Euglena, describe in their motions to the light.” “It has been suggested by the anthropomorphic interpreters of animal conduct that the motion of an animal to a source of light is the same phenomenon as when a human being who has lost his way in the dark is attracted by an illuminated human habitation. As Bohn pointed out, the definite path in which a positively heliotropic animal moves when under the influence of two lights, shows that the anthropomorphic interpretation is as erroneous in this as in any other case. A human being would go to one of two illuminated houses and not toward a point between them, determined by the relative intensity of the two lights.” “When an animal, e. g., a shark or a pigeon is rotated on a turntable, during rotations a nystagmus is observed in the motions of the eyes and sometimes also of the head. If the rotation is not too rapid the eyes move slowly in the same plane but in the opposite direction from the rotation of the turntable, until they form a maximum angle with their normal position in the head; then they rapidly swing back and the whole phenomenon is repeated. This phenomenon is called nystagmus. It depends upon the nerve endings in the semicircular canals, but is not dependent upon the motion or pressure of the lymph in the canals, since the cutting out of the canals in the shark or the plugging up of the canals in the pigeon leaves the phenomenon unaltered. When after some rotation the motion of the turntable suddenly stops, a nystagmus of . the eyes or head in the same plane but in the opposite direction as during the rotation is observed. “Maxwell has shown that if Phrynosoma is rotated on a horizontal plane with constant velocity and the eyes of the animal are closed, compensatory motions of the head are produced as soon as the angular velocity exceeds a certain value which was 8 seconds for a rotation through an angle of 45 ’.” “When a human being has been rotated passively to the right for some time, a t the interruption of the passive motion thqeyes move slowly to the right and return rapidly to the left. Only the slow motions give rise to the sensation of an apparent motion of the objects and hence after the sudden stopping of a passive rotation to the right the objects seem to such a person to move to the left. The geotropic after-effect, after passive rotation to the right, consists in inducing passive compensatory motions to the right, i . e., in the opposite sense of the orientation caused by the apparent motion of the visual objects. Hence in the after-effect the orientation effect of the retina image and the centrifugal effect weaken each other. “Lyon has shown that the phenomena which were formerly described as rheotropism in fish are due to the orientating effect of moving retina images. The reader is familiar with the fact that many fish when in a lively current have a tendency to swim against the current. This phenomenon was believed to be due to the friction of the water. Lyon showed that fish orient themselves just as well when they are put into a closed glass bottle, which is dragged through the water, although in this case they are not under the influence of any friction from the current. When the bottle is not moved the fish swim in any direction inside the bottle. It is obviously the motion of the retina images of the objects on the bank of the brook which causes the “rheotropic” orientation of fish.

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When driven backward by the current or when dragged backward in a bottle thr,ough the water, the objects on the bank of the river seem to move in the opposite direction. The animal being compelled to keep the same object fixed, an apparent forward motion of the fixed object changes themuscles of the fins in such a sense as to cause the animal to follow the fixed object automatically. When such rheotropic fish were kept in an aquarium and a white sheet of paper with black stripes was moved constantly in front of the aquarium the fish oriented themselves against the direction in which the paper and its stripes moved. The phenomenon was more marked in young than in older specimens. All the phenomena of rheotropism ceased in the dark or when the fish were blind.” “These few examples may suffice to show that the theory of tropisms is a t the same time the theory of instincts if due consideration is given to the r61e of hormones in producing certain tropisms and suppressing others. A systematic analysis of instinctive reactions from the viewpoint of the theory of tropisms and hormones will probably yield rich returns. As an example we may quote the fact that diurnal depth migrations of aquatic animals, consisting in an upward motion during the night and a downward motion during the day are in all probability determined by a periodic change in the sense of heliotropism.” “This tentative extension of the forced movement or tropism theory of animal conduct may explain why higher animals and human beings seem to possess freedom of will, although all movgments are of the nature of forced movements. The tropistic effects of memory images and the modification and inhibition of tropisms by memory images make the number of reactions so great that prediction becomes almost impossible and it is this impossibility chiefly which gives rise to the doctrine of free will. The theory of free will originated and is held not among physicists but among verbalists. We have shown that an organism goes where its legs carry it and that the direction of the motion is forced upon the organism. When the orientating force is obvious to us, the motion appears a s being willed or instinctive; the latter generally when all individuals act alike, machine fashion, the former when different individuals act differently. When a swarm of Daphnia is sensitized with COZ they all rush to the source of light. This is a machine-like action, and many will be willing to admit that it is a forced movement or an instinctive reaction. After the COz has evaporated the animals become indifferent to light, and while formerly they had only one degree of freedom of motion they now can move in any direction. In this case the motions appear to be spontaneous or free, since we are not in a position to state why Daphnia a moves to the right and Daphnia b moves to the left, etc. As a matter of fact, the motion of each individual is again determined b p something but we do not know what it is. The persistent courtship of a human male for a definite individual female may appear as an example of persistent will, yet it is complicated tropism in which sex hormones and definite memory images are the determining factors. Removal of the sex glands abolishes the courtship and replacing the sex glands of an individual by those of the opposite sex may lead to a complete reversal of the sex instincts. What appears as persistent will action is, therefore, essentially a tropistic reaction. The production of heliotropism by COZ in Daphnia and the production of the definite courtship of the male A for the female B are similar phe-

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nomena differing only by the nature of the hormones and the additional tropistic effects of certain memory images in the case of courtship. Our conception of the existence of ‘free will’ in human beings rests on the fact that our knowledge is often not sufficiently complete to account for the orienting forces, especially when we carry out a ‘premeditated’ act, or when we carry out an act which gives us pain or may lead to our destruction, and our incomplete knowledge is due to the sheer endless number of possible combinations and mutual inhibitions of the orienting effect of individual memory images.” Wilder D . Bancroft Coal and Its Scientific Uses. B y William A . Bone. 22 X 15 cm; p p . New York: Longmans, Green and Co., 1918. Price: $7.oo.-In 1865 Jevons said that “Coal in truth stands not beside, but entirely above, all other commodities. It is the material source of energy of the country, the universal aid-the factor in every thing we do. With coal almost any feat is possible or easy; without it we are thrown back into the laborious poverty of early times. . . The progress of science, and the improvement in the arts will tend to increase the supremacy of steam and coal.” The author has treated the subject under the following headings: introductory; the origin and formation of coal; the chemical composition of coal; the combustion of coal; the principles governing combustion and heat transmission in boilers; domestic heating; the smoke nuisance and its abatement; general considerations relating to the use of gaseous fuels derived from coal; the carbonization industries; the complete gasification of coal; water gas and its applications; fuel economy in the manufacture of iron and steel; economy of fuel attainable in the blast furnace by the use of dry blast; power production from coal; surface combustion. The following extracts, pp. 23, 68, 164, 178, 221, 224, 438 give some idea of the book. “Although many classes and varieties of coal occur in Nature, all of them represent some stage or product of the primary decomposition and subsequent transformations, under the combined influence of slowly increasing pressure, and possibly also of temperature, of the vegetable debris of primaeval forests and swamps. This process has gone on in several of the great geological periods, and, so far as its early stages are concerned, is being repeated to-day under somewhat different conditions in our modern peat bogs and deltas, where enormous masses of water-logged vegetable debris are decomposing under bacterial influence. “A consideration of the geographical distribution of the world’s principal coalfields shows that all the important fields adjacent to the North Atlantic and Arctic areas (which include nearly all the fields of the North-West Europe and in the eastern part of North America) originated in what geologists call the Carboniferous Period of the Primary Era; while what may be termed the ‘Indian Ocean’ group of coalfields (which include those of China, India, Australia, and South Africa) originated in the somewhat later Permo-Carboniferous Period. Mesozoic coals are found in the interiors of North America and Asia (intracontinental group) ; while Tertiary coals are chiefly found in what may be termed the Pacific borderland (west of North America, Japan, and New Zealand), as well as in regions bordering on the Gulf of Mexico and the Mediterranean. “The great coalfields of the Carboniferous System originated in a new monster vegetation flourishing in a rich virgin soil, with an equable if not subxu

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tropical climate, and large areas of shallow sea, to which great quantities of sediment were borne from rivers. Vegetable tissue has in all ages, then as now, been built up by the action of chlorophyll under the influence of sunlight, stimulated by minute quantities of mineral salts drawn in by the roots, upon atmospheric carbon dioxide and moisture, which action sets up a complex series of chemical changes, with the intermediate formation of sugars and starches, ultimately resulting in the production of celluloses and ligno-celluloses, as the basis of all woody tissue.” “In selecting coal for any particular purpose, the following points may usefully be borne in mind : “ I . The best gas-coals are those in which the 0:H ratio is approximately 2 . 0 . They usually yield 32 to 38 percent of volatiles a t 900” (reckoned on the dry ashless coal), and a fairly porous coke. “ 2 . The best coking coals usually yield between 20 and 30 percent of volatiles a t 900” C. They are strongly caking, and have a ferruginous ash. “3. The best steam-coals are found among those which yield between I O and 2 0 percent of volatiles a t 900” C; they are non-caking, or only feebly so and they should have a non-ferruginous ash. “4. For gas generation, where the whole of the coal is to be gasified in a ‘producer’ under the influence of a mixed steam-air blast for the making of ‘Producer Gas,’ it is best to select, whenever available, either a non-caking or feebly caking coal with, if possible, an infusible non-ferruginous ash. Strongly caking coals are to be avoided. “ 5 . The coals freest from sulphur, arsenic, and with the purest end lowest ash contents are the anthracites.” “When a fresh charge of raw coal is introduced into the furnace of, say, a boiler, it first of all undergoes a destructive distillation, whereby a number of combustible gases, tarry vapors and steam are expelled. The gaseous products consist chiefly of hydrocarbons (methane with smaller proportions of ethylene, benzene, and probably also ethane), hydrogen, and carbon monoxide, whilst the tarry vapours are mingled with a certain proportion of finely divided carbon (soot). The ‘volatile’ combustion constituents thus evolved from the upper portion of the fuel bed will amount in all to between 1 5 and 2 5 percent of the weight of the ash-free coal charged, and the oxygen needed for this combustion must be furnished by what is sometimes termed a ‘secondary’ air supply which is usually introduced through adjustable openings in the doors of the furnace, or (may be) also a t the fire-bridge, in such a manner that it mixes with the combustible gases and vapours a t or near the top of the fuel bed. The ensuing combustion causes the well-known development of smoky flames in the furnace after each addition of fuel. “The combination of the residual coke (carbon) takes place in the lower layers of the fire by means of the ‘primary’ air supply drawn in through the fire-bars, the evidence of which may be seen by looking a t the incandescent mass of fuel in the furnace towards the end of the interval between two successive chargings of the coal. “Accepting this as an approximately true view of the outward and visible sequence of events in the furnace, it is a t once evident that we have to deal with a t least two distinct cases of combustion, namely ( I ) that of solid carbon

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in the lower layers of the fire, and ( 2 ) that of the combustible ‘volatiles’ (gases and vapours) in or above the upper layers.” “The combustion of the heavier hydrocarbons which constitute the tarry vapours produced by the distillation of the coal is a much more difficult matter, inasmuch as their complex more molecular constitution renders them not only more resistant to oxygen attack, but also prone, under the roasting influence of heat, to form still denser molecular aggregates by a series of internal condensations Without doubt the production of the mixture of soot and dense hydrocarbons which constitute black smoke is largely due to this circumstance. The best way of counteracting it is to ensure a uniform supply and distribution of ‘preheated’ air, so as to keep the interacting gaseous medium well above the ignition point of the tarry vapours it contains, and to ensure that all parts of it are sufficiently, though not excessively, supplied with the necessary oxygen for the maintenance of vigorous combustion. Also, devices which will cause the burning mixture to impinge on incandescent fire-brick surfaces in the furnace, thereby accelerating combustion, will undoubtedly minimize, even if they do not altogether prevent, smoke production. “It is obvious that, so long as a coal is ‘free-burning,’ the smaller the amount of volatile matter it contains the less will be its liability to cause smoke, and, inasmuch as smoke production is always a sign of incomplete combustion, the more efficiently can it be burnt Hence arises the good reputation of the celebrated semi-bituminous Welsh ‘steam-coals,’ containing from I O to I j percent of volatile matter, which burn almost smokelessly. As, however, such smokeless coals are only available in certain favoured localities, it has been frequently suggested that, as a good means of preventing smoke, suitable bituminous coals might be submitted to a preliminary process of expelling or decomposing their smoke-producing constituents by low temperature distillation in a separate apparatus before being burnt in boiler furnaces and the like. If such a process could be carried out economically so as to yield ‘semi-coke’of sufficient strength, the problem of boiler firing with solid fuel would be much simplified. Even then, however, the achievement of really efficient combustion would still depend upon the proper regulation and distribution of both primary and secondary air supplies, and the maintenance of uniform conditions in the furnace. And for this purpose, both a good draught and effective means of regulating it, are absolutely essential as a prime condition of success.” “Some idea of the wastefulness of our British open fireplaces and kitchen ranges may be gained from the fact that, whereas with a population of 46 millions we annually consume in our houses about 36 million tons of coal, in Germany, with its population of 67 millions and its severer winter climate, where closed stoves and ranges are universally employed, only 17 million tons are so burned. In other words, each inhabitant of the United Kingdom requires a domestic consumption of I j cwts of coal per annum, as against only 5 cwts. in Germany ” Many reforms in the construction of house firegrates are due to the pioneering work of Mr. Teale. In a pamphlet published in 1883, he tells us that “his ideas embody a combination of two conditions, namely, one, that no current of air should pass through the grate a t the bottom of the fire; the other, that the space or chamber under fire should be kept hot. He laid down seven

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rules to be observed in the construction of fireplaces, which in substance are as follows: “ I . As much firebrick and as little iron as possible to be used. “ 2 , The back and sides of the fireplaces should be constructed of firebrick. “ 3 . The back of the fireplace should lean or arch over the fire so as to become heated by the rising flame, whereby smoke is consumed, and much more heat is radiated into the room. “4. The bottom of the fire or grating should be deep (9 to 1 2 in.) from before backwards, in order that the fire may be made horizontal and slow-burning instead of vertical and quick-burning. “5. The slits in the grating should be narrow ( I / d to 3,’s in. in width). “6. The bars (if any) in front should be narrow (less than in. thick) and not more than four in number for an ordinary fire. “7. The chamber beneath the fire should be closed in front by a shield or ‘economizer,’ so as to stop all currents of air that would pass under the grate and through the fire.” “On the assumption that power may be most efficiently applied to industry by the medium of electricity, the Committee [on Coal Conservation] are of the opinion that the present system of electrical power distribution throughout the country, which is undertaken by over 600 authorities in as many separate districts, is both technically wrong and commercially uneconomical. The present average size of generating stations is stated to be only 5000 H. P., or about one-fourth of what should now be the smallest generating machine in a power station. The Committee accordingly made a number of recommendations for the supervision of the present system by a comprehensive scheme for Great Britain, of which the first six may here be quoted:“ I . It is essential that the present inefficient system of over 600 districts should be superseded by a comprehensive system in which Great Britain is divided into some sixteen districts, in each of which there should be one authority dealing with all the generation and main distribution. “ 2 . Centres, or sites, suitable for electric generating purposes should a t once be chosen on important waterways as the future main centres of supply for each of the districts into which the country is to be divided. “ 3 , The sites so chosen should be as large as possible, having in view the land available in suitable localities, and should have ample water and transport facilities. Land is required, not only for the power stations themselves-which for the sake of security and safety would have to be suitably subdivided, that is they would not be contained all in one building-but for the processes involved in the extraction of by-products from the coal before i t is used for the production of power, where such extraction is found to be justified. It is also required for the development of electro-chemical processes, which may be most conveniently carried on in close proximity to the power plant. This condition entails the sites being chosen outside, not inside, towns. The health of the great industrial centres and the congestion of the railway lines in their neighborhood would be radically improved by arranging that the conversion of coal into motive power was carried out away from the densely populated centres. “4. Plans should be prepared for the construction immediately after the war on these sites of the first instalment of large super-power plants capable,

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first, of supplying through a comprehensive electric power distribution system which must also be arranged for, the existing demands of the community; and, secondly, of supplying electrical energy a t the lowest possible price for new processes and manufactures. “ 5 . Such plants would be designed so that, as methods are perfected for extracting by-products from the fuel, before using it for the purpose of the production of electric power, the by-product plant can be combined with the power plant. Each site should be laid out with this in view, and with a view to the unrestricted extensions of the plant as required. “ 6 . Power available from surplus gas or waste heat should be turned into electrical energy on the spot in local plants which would feed into the main distribution system. As regards waste coal, i. e., coal which it does not a t present pay to bring to the surface-this could, where transport was the ruling consideration, also be used on the spot.” Wilder D . Bancroft Fractical Physiological Chemistry. B y Phitilip B . Hawk. Sixth edition, revised and enlarged. 24 X 17 crn; pp. xiv 661. Philadelphia: P. Blakiston’s Son and Go., 1918. Price: $3.50.- “The book has been thoroughly revised in an attempt to bring it strictly up to date. In view of the great clinical importance of the chemical phases of the phenomena of acidoses a new chapter

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on acidosis has been introduced. The chapters on metabolism, blood analysis, gastric digestion, and quantitative analysis of urine have been expanded considerably, and the question of growth has been treated experimentally. Two radical changes in the quantitative section are the substitution of Van Slyke’s procedure for all former methods for the determination of acetone bodies in urine and the elimination of all methods for the determination of urea, except those based upon the use of urease.” The titles of the chapters are: enzymes and their action; carbohydrates; salivary digestion; proteins ( 2 ) ; nucleic acids and nucleoproteins ; gastric digestion; gastric analysis; fats; pancreatic digestion; intestinal digestion; bile; putrefaction products; feces; blood and lymph; blood analysis; acidosis; milk; epithelial and connective tissues; muscular tissue; nervous tissue; urine ( 5 ); metabolism. “Of all the various elements of the protein molecule, nitrogen is by far the most important The human body needs nitrogen for the continuation of life; but it cannot use the nitrogen of the air or that in various other combinations as we find it in nitrates, nitrites, etc. The nitrogen in the protein molecule occurs in a t least four different forms, as monamino acid nitrogen, as diamino acid nitrogen or basic nitrogen, as amide nitrogen, and as guanidine residue (P. 64).” From reliable experiments made upon lower animals and man it is evident that the gastric juice is secreted as the result of stimuli of two forms, psychical stimuli and chemical stimuli. The psychical form of stimuli may be produced by the sight, thought, or taste of food; and the chemical stimuli may be produced by certain substances, such as water, milk, the excretives of meat, etc., when coming in contact with the stomach mucosa. The stimulatory power of water has been demonstrated very strikingly. The claim that the drinking of water with meals is harmful, because such a procedure causes a dilution of

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t h e gastric juice, has no basis in fact. The drinking of water with meals by normal individuals has been found to be accompanied by a more economical utilization of the ingested proteins, fats and carbohydrates. Various other desirable, and no undesirable, features have been demonstrated as accompanying or following such dietary procedure. No experimental evidence has been submitted which can justly be interpreted as showing any harmful influence to accompany or follow the drinking by normal persons of all large quantities of water a t meal time (p. 138).” “The processes involved in the coagulation of the blood are not fully understood. Several theories have been advanced and each has its adherents. The theory which appears to be fully as firmly founded on experimental evidence as any is the following. Blood contains a zymogen called prothrombin which combines with the calcium salts present to form an enzyme known as thrombin or fibrin-ferment. When the blood is drawn from a vessel the fibrin-ferment a t once acts upon the fibrinogen present and gives rise to the formation of fibrin. This fibrin forms in shreds throughout the blood mass and.holding the form elements of the blood clot. The fibrin shreds contract gradually, the clot assumes a jelly-like appearance, and the yellowish serum exudes. If, immediately upon the withdrawal of blood from the body, the fluid be stirred rapidly or whipped thoroughly with a bundle of coarse strings, twigs, or a specially constructed beater, the fibrin shreds will not form a network throughout the blood mass; but instead will cling to the device used in beating. In this way the fibrin may be removed and the remaining fluid is termed defibrinated blood (p. 260).” “The difference between the freezing-point of normal urine and that of It is subject to very pure water varies ordinarily between -1.3’ and -2.3’. wide fluctuations when conditions are unusual. For instance, following copious water or beer drinking, the difference may be only -0.2’ whereas it may be -3 or more on a diet containing much salt and deficient in fluids. The freezand is not subject to the ing-point of normal blood is generally about -0.56‘ wide variations noted in the urine, because of the tendency of the organism to maintain the normal osmotic pressure of the blood under all conditions. Variamay be due entirely to dietary conditions; tions between -0.5 I ’ and -0.62 b u t any marked variation can, in most cases, be traced to a disordered kidney function (p. 393).” “As a result of the work of different experimenters, certain accessory food substances, ‘growth-promoting substances,’ or vitamines, as they are variously termed, have been shown to be of great importance in nutrition. The exact character of these substances has not been established. There are two distinct accessory food substances, one soluble in fats and called ‘Fat-Soluble -4,’ the other soluble in water and called ‘Water-Soluble B.’ The substances have a rather wide distribution. The fat-soluble vitamine is present in milk fat, egg yolk fat, beef fat, cod liver oil, ‘oleo oil,’ margarins, cabbage and alfalfa leaves, rye, and the seeds of flax, hemp, millet, and sunflower. The watersoluble vitamine occurs in milk, rice (unpolished), yeast, peanuts, pancreas, and kidney bean. Certain animal and vegetable products contain both the vitamines. Among these are whole milk, cotton seed, soy bean, the kernel of maize and oat, and the kernel and embryo of wheat. In order that a diet may be adequate

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for growth, it must contain a satisfactory quota of these accessory food substances in addition to protein, proper in kind and amount, suitable inorganic matter, and enough fat and carbohydrate to yield the required energy (p. 585).” The reviewer would have welcomed a discussion of the possible reasons why a fat man utilizes his food quite differently from a thin man. This is the most important problem in metabolism and we know practically nothing about it, which makes it the more necessary that the problem should be formulated and brought to the front as often as possible. Wilder D . Bancroft Electro-Analysis. By Edgar F. Smith. Sixth edition. 20 X 14 cm; pp. P . Blakiston’s Son and Co., 1918 Price: $z.50.-1n the preface to this edition the author says: “The methods of electro-analysis are finding their way into all laboratories; indeed in many works every provision has been made to apply them. Since the appearance of the last edition of this book, comparatively few new fields or new and important advances have been made, so that in the present revision, while making place for references to all contribution which have been published, there are comparatively few additions to the main text. Attention is directed particularly to the improved double cup, p. 316, in which hundreds of halides have been analyzed successfully. The new device ensures complete success and removes every doubt which may have arisen in regard to the efficacy of the apparatus first suggested in the determination of anions and cations. Other additions to the text will be noticed a t once, so that in its present form there is presented the most recent and complete picture of the subject to which the book is devoted; not that electro-analysis has attained perfection, for this would be, in no sense, true as so much remains for study; but the book brings together all that has been found reliable, by the test of experience, and offers simultaneously the latest results gathered in recent years Wilder D . Bancroft from widely removed centers.” 13

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Introduction to Organic Chemistry. B y J . T . Stoddard. Second edition. 18 X 13 cm; pp. x f 423. Philadelphia: P . Blakiston’s Son and Co., 1918. Price: $~..fo.--“The book is considerably smaller than many of the text-books on the subject; but it is believed that it is none the less complete in all the essential matter which is properly presented in a first course. The larger text-book is apt to bewilder the student by brief descriptions of too many compounds of minor importance, or to fill too many pages with discussions which can be conducted to better advantage by the lecturer.” The sections which have been rewritten in the second edition are those on the natural oils and fats, on uric acid and the purine bases, and on the proteins. There are a few points which the reviewer a t least would like to see amplified. Why do ethyl and methyl chlorides, p. 32, burn with a green-edged flame? The alumina method of making ethylene is better than the phosphoric acid one, p. 46. Why does fusel oil, p. 67, distill with alcohol though having a much higher boiling-point? Since the vapor of acetic acid is hardly decomposed when led through a red-hot tube, p. 97, why is it so difficult to oxidize acetaldehyde to acetic acid above IOO”? Reference might well have been made to the difference between calcium and sodium hydroxides in causing the hydrolysis Wilder D . Bancroft of fats.

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