parative study of myths current among American Indians and in the interpretation of them. JOHN R. SWANTON SMITHSONIAN INSTITUTION, The Genus Phoradendron. By WILLIAM TRELEASE, Professor of Botany in the University of Illinois. Published by the University. Octavo, pp. 224, pls. 245. Price, paper, $2.00; cloth, $2.50. It is fortunate for botanists that the author of this excellent treatise has made so thorough a revision of the genus Phoradendron instead of being content with merely attempting to straighten out the tangle existing in regard to the group of related forms hitherto known as Phoradendron flavescens, as he first contemplated. The author notes that Engelmann has shown too great a conservatism in his published studies of the various forms of species of the genus, by later withdrawing segregates of P. flavescens that he formerly had recognized, and that in continuing the work of Engelmann, also being influenced by his views, Torrey allowed a number of forms which he had designated as new species to lie unpublished in the Torrey herbarium. The author in addition to making a critical study of the abundant data and material of North American species collected by Engelmann, Torrey and others in the great herbaria of this country, visited those of Europe and extended the investigation to the collection of West Indian and South American species by Urban, Martins and others. This has enabled him to make a careful comparison of numerous types and variants of species of the genus, and to more carefully discriminate between varieties and species. He recognizes 262 differentiable forms, most of which he has classified as species. In this matter he apparently does not share the conservatism of Engelmann and Torrey. Of the species he now recognizes, 154 are listed from North America and 124 from South America. The genus is separated into two primary groups, the Boreales and the Equatoriales, plants of the former are constantly without, and the latter constantly with cataphyls on their foli age shoots. Both groups contain species destitute of expanded foliage, which are well represented by Phoradendron juniperinum in the southwestern United States. All of our species belong to the Boreales, those of Mexico and Central America to both primary groups, and those of the West Indies and South America wholly to the Equatoriales. These primary groups are each divided and then subdivided, making finally in all groups 55 minor subdivisions. The book contains 224 pages of descriptive matter including very good and usable keys; these are supplemented by indexes of collectors, occurrence, and names. The illustrations, 245 full sized plates, are indeed works of art but are also true to nature. Few books of this class are so fully and beautifully illustrated. GEORGE G. HEDGCOCK MECHANICAL PROPERTIES OF WOOD DETERMINED A NUMBER of fundamental laws governing the properties of wood, such as those covering the relations between strength and specific gravity, and between strength and moisture content, are laid down in a bulletin just issued by the Department of Agriculture. In this publication are presented the results of about 130,000 strength tests, probably the largest single series ever run on one material, made by the Forest Products Laboratory of the Forest Service on 126 species of American woods. The laws derived from the tests cover the general relations existing between mechanical and physical properties of each species, and also the general relations existing between these properties irrespective of species. The results ought to prove of great value wherever knowledge of the properties of wood is essential. They have, for example, made possible the preparation of accurate tables showing all the needed strength properties for the woods used in airplanes. With these as a basis, specifications can be drawn up to eliminate all material that does not meet the exacting requirements of this highly specialized use. The data also permit of the proper choice of substitutes for woods which have become scarce or unobtainable. Here again the airplane may be cited, since the supplies of some woods ordinarily used in airplane construction are insufficient to meet the present building program of the United States and its allies. Among the relations between mechanical and physical properties of wood for which laws have been obtained are static bending-specific gravity, impact bending-specific gravity, compression parellel to grain-specific gravity, compression perpendicular to grain-specific gravity, static bending-moisture content; impact bending-moisture content, compression parallel to grain-moisture content, compression perpendicular to grain-moisture content, shrinkage-moisture content. The bulletin, the authors of which are J. A. Newlin and Thomas R. C. Wilson, is entitled "Mechanical Properties of Woods Grown in the United States," and is No. 556 in the Department of Agriculture series. which has proved so simple and convenient that it seems desirable to suggest it to others. In its first form it consisted merely of a thin watch-glass 45 to 50 mm. in diameter, cemented by sealing-wax to the flattened end of a piece of inch lead wire 12 inches long. If the muscle of a gastrocnemius-sciatic preparation is mounted on a muscle lever, the edge of the watch-glass may be brought very near to the muscle and the whole nerve may be allowed to lie in the liquid to be applied, as for example, a solution of sodium citrate or barium chloride. The construction is so simple, requiring no special skill and only a few minutes of time, that it was used in this way for two or three years. Later, Mr. L. A. Ray, technician, devised the following more permanent construction. A small bit of glass rod is fused to the bottom of the watch-glass. The rod is then melted and pulled in two at a point about to inch from the bottom of the glass, and is held in the flame till a small knob forms on the end. A hole is punched in the flattened end of the lead rod, the glass rod is inserted and the joint made fast with cement. The knob on the end of the glass is held firmly in place by the cement. The accompanying figure of a section of watch-glass and rod will make the whole arrangement perfectly obvious. S. S. MAXWELL RUDOLPH SPRECKELS PHYSIOLOGICAL LABORATORY, UNIVERSITY OF CALIFORNIA THE URINE OF THE HORNED LIZARD VAUQUELIN,1 in reporting the first analysis of reptilian urine, in 1822, stated that it was composed almost entirely of uric acid, and since that time this fact has been interpreted by various observers as an adaptation to the conditions of life in arid regions, where animals obtain their only external water supply in very limited quantities in the food substances, as this type of nitrogenous excretion involves practically no water loss. The reptiles of arid regions have been known for some time to excrete practically all of their waste nitrogen in the form of uric acid and its salts, while, on the other hand, birds and aquatic and semiaquatic reptiles may excrete considerable amounts of urea. 1 Vauquelin, Louis Nicolas, "Examen des excrémens des serpens que l'on fait voir en ce moment à Paris, Rue Saint-Nicaise," Annales de Chimie et de Phisique. 2me Serie, Tome 21, p. 440, 1822. Two boas, species not stated, were the source of the urine examined in this case. Uric acid had also been associated with reptiles as early as 1793, when a "pasty deposit" found in the bladder of a tortoise by Vicq-d'Azyr was found to contain this substance. The urine of the horned lizard is excreted in the dry form at the same time as the feces, from which it is separated by a constriction of the common mass, the material voided at any one time having roughly the shape of a dumbbell, one of the enlargements being composed of urine and the other of fecal matter. The following figures for the composition of the urine of Phrynosoma cornutum (specimens obtained at Alamogordo, N. M.) have been obtained recently in the laboratory of physiological chemistry of the University of Illinois, the work having been undertaken at the suggestion and under the direction of Dr. H. B. Lewis. SOCIETIES AND ACADEMIES THE one hundred and ninety-third regular meeting of the American Mathematical Society was held at Columbia University on Saturday, October 27. The attendance at the morning and afternoon sessions included thirty-five members. Professor Oswald Veblen occupied the chair, being relieved by Professor L. P. Eisenhart. The council announced the election of the following persons to membership in the society: Dr. J. V. DePorte, State College, Albany, N. Y.; Mr. J. W. Lasley, Jr., University of North Carolina; Mr. Vincente Mills, Philippine Bureau of Lands; Professor B. M. Woods, University of California. Five applications for membership were received. A committee was appointed to audit the accounts of the treasurer for the current year. A list of nominations for officers and other members of the council was prepared and ordered printed on the official ballot for the annual election at the December meeting. The Secretary was directed to procure insurance to the amount of $10,000 on the library of the society, which is deposited in the Columbia Library. The following papers were read at this meeting: R. D. Carmichael: "Elementary inequalities for the roots of an algebraic equation.'' Louise D. Cummings: "The two-column indices for triad systems on fifteen elements." G. A. Pfeiffer: "On the continuous mapping of regions bounded by simple closed curves. J. F. Ritt: "On the differentiability of asymptotic series." W. B. Fite: "Concerning the zeros of the solutions of certain linear differential equations.'' J. E. Rowe: "Hexagons related to any plane cubic curve." G. D. Birkhoff: "On a theorem concerning closed normalized orthogonal sets of functions with an application to Sturm-Liouville series." Edward Kasner: "Systems of circles related to the theory of heat." O. E. Glenn: "Systems of invariants and covariants of Einstein's theory of relativity." J. K. Whittemore: "Theorems on ruled surfaces.' R. L. Moore: "On certain systems of equally continuous curves. R. L. Moore: "Continua that have no continua of condensation.' "" J. R. Kline: "Necessary and sufficient conditions, in terms of order, that it be possible to pass a simple continuous arc through a plane point set." Oswald Veblen: "On the deformation of ncells.'' Oswald Veblen: "Deformations within an n-dimensional sphere." The San Francisco Section met at the University of California on October 27. The Southwestern Section will meet at the University of Oklahoma on December 1. The Chicago Section will meet with the Mathematical Asssociation of America at the University of Chicago on December 2829. The annual meeting of the society will be held at Columbia University on December 27-28. F. N. COLE, Secretary SCIENCE FRIDAY, NOVEMBER 30, 1917 THE PRODUCTION OF SCIENTIFIC KNOWLEDGE1 THE great value of scientific research both to the industries and to the nations at large is now generally recognized throughout the world and the last few years have seen a remarkable increase in the efforts made to stimulate the production of scientific knowledge. In 1914 the American Association for the Advancement of Science appointed a Committee of One Hundred to inquire into the steps which should be taken for the increase of scientific research in the United States and the work of this committee has been continued and expanded by the National Research Council. Among the European nations there is a great awakening to the national value of scientific research. The British government has appointed a Department of the Privy Council to deal with the subject, while it is announced that in France a new national laboratory on a very large scale has been projected. In Australia the government has appointed a special department to consider what steps should be taken for the organization and development of research work in the Commonwealth, and in Canada the matter has been the subject of government inquiry and solicitude. The increase of scientific knowledge can be divided into three steps: first, the production of new knowledge by means of laboratory research; second, the publication of this knowledge in the form of papers and abstracts of papers; third, the digestion of the new knowledge and its absorp 1 Being a paper read before the Rochester Section of the Optical Society of America, October 23, 1917. tion into the general mass of information by critical comparison with other experiments on the same or similar subjects. The whole process, in fact, may be likened to the process of thought. We have first the perception by means of the senses. The percept is then stored in the memory and in the mind is compared with other previously stored percepts, and finally forms with them a conception. I desire in this paper to consider the methods by which these three sections of the production of knowledge may be carried on, to suggest an arrangement of laboratories to produce experimental results dealing with any branch of science, then to consider how the knowledge so obtained may best be stored and classified and finally the methods to be employed to make the results of scientific research available for application. 1. RESEARCH WORK The agencies engaged in scientific research are of several kinds. The traditional home of research work is in the university, and the bulk of the scientific production of the world comes from institutions connected with teaching. The industries are more and more supporting research laboratories, a large number of which contribute to the general fund of scientific knowledge by publishing the results which they obtain, and some of which are engaged upon purely scientific work of no mean order. Consulting and technical laboratories engaged in industrial work make frequent contributions to science, and there are some very important laboratories engaged in pure research work which are supported by philanthropic foundations. The classification of research laboratories is not altogether an easy task. They may obviously be classified according to the source of the funds which support them; that is, we may classify them as uni 1 versity laboratories, industrial laboratories, government laboratories, institution laboratories, and so on, but if we look at them simply in the light of the research undertaken, this does not seem to be altogether a logical classification since there is little distinction between the work done in some university laboratories and some industrial laboratories, and the work of the government and institution laboratories again overlaps that of the two former classes. The University of Pittsburgh, for instance, has an industrial laboratory where definitely technical problems are dealt with. The research work on photometry done at Nela Park and at Cornell University would seem to be similar in kind, and work on physical chemistry or on the structure of chemical compounds is of the same type, requires the same class of workers, and produces the same results, whether it be done in a university, in a laboratory of the Carnegie Institution or in such an industrial laboratory as that of the General Electric Company. It is equally difficult to classify laboratories according to the purpose for which researches are avowedly carried on. Most university laboratories are willing to undertake work of industrial value, and, indeed, some specialize in such problems; while many industrial laboratories are quite willing to carry out a research of purely academic and theoretical interest provided the problems involved bear a relation to the general work of the laboratory. A useful classification of laboratories can, however, be obtained if we consider whether the problems investigated in a laboratory are all connected with one common subject or whether the problems are of many kinds, having no connecting bond of interest. I would suggest that the first type of laboratory might be called "con |