as Cold Spring Harbor, on June 25, was follows: President Stewart Paton's address: "Democracy's opportunity." R. H. Johnson: Some eugenical aspects of the distribution of wealth." Madison Grant: "The present racial outlook in the world at large." A. H. Estabrook: "The eugenical bearing of psychological work of the army." A. J. Rosanoff: "Preliminary report of a study of the prevalence of chronic psychoses in the population of the State of New York." Anna M. Peterson: "The eugenical aspect of custodial institutions for women." F. Stuart Chapin : "The scientific aspects of field work in the social sciences." C. B. Davenport: "Heredity of twins." H. H. Laughlin: "The eugenical provision of the constitution of the German republic." FREE public lectures are being delivered in the lecture hall of the Museum Building of the New York Botanical Garden, Bronx Park, on Saturday afternoons, at four o'clock, as follows: July 17. "Spoilage of fruits and vegetables during transportation and storage,'' F. C. Meier. July 24. "The state park at Devil's Lake, Wisconsin," Dr. A. B. Stout. July 31. "Flowers for the summer garden,'' G. V. Nash. August 7. "Diatoms-plants of beauty seen through a microscope," Dr. M. A. Howe. August 14. "Through the Philippines with a kodak," Dr. H. A. Gleason. August 21. "How to know, gather and cook the puffballs," Dr. W. A. Murrill. August 28. "A trip to Colorado," Dr. F. J. Seaver. In order to provide a method for viewing the collections of the garden under guidance, a docent leaves the front door of the museum building every week-day afternoon at 3 o'clock, to escort all who may wish to accompany him. The routes are as follows: Monday: Hemlock Forest, Mansion and Herbaceous Garden. Tuesday: Pinetum. Wednesday: Fruticetum and North Meadows. Thursday: Deciduous Arboretum, Public Conservatory Range 2, Nurseries, and Propagating Houses. Friday: Public Conservatory Range 1. Saturday: Museums. UNIVERSITY AND EDUCATIONAL NEWS DR. RODNEY HOWARD TRUE, of the U. S. Department of Agriculture, has been appointed professor of botany in the University of Pennsylvania, to succeed Dr. John M. Macfarlane, who recently resigned. DR. WALTER TAGGART has been appointed Blanchard professor of chemistry and director of the chemical laboratory of the University of Pennsylvania, to succeed Dr. Edgar F. Smith. DR. H. R. KRAYBILL, of the Bureau of Plant Industry, has been appointed professor of agricultural chemistry and head of the department of chemistry of New Hampshire State College. ADDITIONAL appointments in Colorado College for 1920-21 include, as assistant professor of geology, Mr. I. A. Keyte, B.S. (Missouri), recently head of science work in the Colorado Springs High School, and, as instructor in physics, Mr. Elmer Furnquist, A.M., (Illinois), recently an instructor in that insti tution. REINHOLD F. A. HOERNLE, assistant professor of philosophy at Harvard University, has resigned in order to accept a professorship at Durham University. DR. W. J. DAKIN, professor of biology in the the University of Western Australia, has been appointed to the Derby chair of zoology, University of Liverpool, in succession to the late Professor Leonard Doncaster. Dr. I. M. Heilbron, professor or organic chemistry at the Royal Technical College, has been appointed to the chair of organic chemistry. DR. BENJAMIN MOORE, of the research staff at Oxford, has been appointed to the new chair of biochemistry. DISCUSSION AND CORRESPONDENCE INTERSEXES IN DROSOPHILA AND DIFFERENT TYPES OF INTERSEXUALITY TO THE EDITOR OF SCIENCE: In your issue of March 26, 1920, there appeared an important article by Dr. Sturtevant, in which he proved that intersexuality may be produced in Drosophila simulans by the action of a mutant gene. He concludes with the remark: It has been assumed by Goldschmidt, Hertwig, Banta, and others working with intersexes that in their animals the normal sex-determining mechanism itself was failing to function as usual. The present example shows that such an assumption can not be accepted without proof.1 May I be allowed to point out some very important distinctions between this present example and the best worked-out of the others, namely Goldschmidt's intersexual moths (Lymantria). (1) Sturtevant's intersexual Drosophila are all females. Goldschmidt has obtained intersexes in both sexes. (2) The gonads in Sturtevant's example are described as "minute, if present." In Lymantria, instead of such marked reduction occurring, the gonad is transformed, partly or wholly, into that typical of the other sex. (3) Most important of all, Sturtevant's flies appear to be all of one type or grade of intersexuality. Goldschmidt's moth intersexes, both male and female, form a continuous series from normality to complete sex-reversal. (4) Goldschmidt's analysis of his material has shown that the Lymantria intersexes are zygotes which have started development as individuals of one sex, but at a given point have been switched over to continue as individuals of the other sex. The degree of intersexuality depends on the point of time in development at which the change occurs. It is essential to have an analysis of the Drosophila case from this point of vew, before further comparison is profitable. (5) When a highly intersexual female Lymantria which is functional as a male is mated with a normal female, the sex-ratio in the resulting broods is what would be expected if both parents were of Z W chromosome constitution; the same is true when, instead of highgrade intersexes, such individuals of all male broods as must be supposed to be transformed females are bred from. With these differences between the intersexuality of Drosophila and that of Lymantria, 1 To this list should be added Harrison, Jour. Genetics, 9, 1919, p. 1. In we can not be sure that the two are quite comparable, or due to the same set of causes. conclusion, it may be said that the Columbia School itself has made it exceedingly probable that the function of the sex genes is normally to initiate one series when present in two doses; the one series of reactions allowing of the appearance of the structures and instincts of one sex, the other of those of the other sex. If this is so, then there is theoretically nothing whatever against the possibility of these series of reactions, and the physiological states to which they give rise being altered, (1) by the mutation of independent genes (as appears undoubtedly to be the case in D. simulans); (II) by an alteration in the balance between the sex-genes and other factors influencing development, (as would seem more than probable in Lymantria); or, (III) by external agencies (as apparently in Hertwig's and Kuschakewitsch's experiments on frogs and Miss King's on toads). The burden of proof, in the present state of our knowledge, lies even more on the upholders of gene-produced intersexuality than on the upholders of the balance theory, but quite possibly both are right. NEW COLLEGE, Oxford, May 1, 1920 JULIAN S. HUXLEY THE ORIGIN OF OIL A. W. McCoy has published in Journ. Geol. XXVII. (1919), pp. 252-262, evidence that crushing oil shale converts some of the solid organic matter into oil. The conditions of the experiment seem to preclude any chance for much general heating of the mass of shale used. Can some mathematical physicist tell us whether a strain or shear would cause a high temporary temperature at the point of rupture? The heat would be absorbed by the adjacent rock and would not greatly increase the temperature of the whole mass, unless the quantity of heat were large. Yet the temperature at some points might be high enough for a very short time to cause the dissociation of the organic molecules adjacent to these points. The effect probably would be concentrated on the surfaces of maximum strain and shear. The results of this enquiry may be of fundamental significance in theories of the origin of oil. The writer will appreciate any information thereon. CHESTER W. WASHBURNE 60 LIBERTY STREET, NEW YORK CITY THE CAUSES AND PREVENTION OF AFTER CORROSION ON THE BORES OF FIREARMS1 THE report of an experimental study, containing also a careful review of the scientific, patent, and trade literature and a compilation of empirical experiences which have variously attributed after-corrosion on oiled bores as due to powder acids, diffusing gases, primer acids, metal fouling, and chlorides. Humidity relations, chemical examination of the corrosive residue, special ammunition, and a study of many so-called "gun oils" and "nitrosolvents" showed: The infantry service cartridge leaves no nitrocellulose or acid residue. The aftercorrosion is caused by (1) the deposition of a water soluble salt or salts capable of giving corrosive solutions, (2) the presence of a humidity high enough to form a liquid film, and (3) the presence of oxygen. In the service ammunition, the decomposition of the chlorate of the primer furnishes the only water soluble salt. Pits and tool wounds retain this, so that it can not be removed mechanically. It may be dissolved by water. Corrosion may also be prevented by stoppering the bore or by altering the composition of the primer. A number of the non-aqueous compositions sometimes recommended for cleaning rifles are of no value. Their virtues apparently rest on tests conducted at humidities so low that no corrosion could occur. The paper is illustrated with photographs and photomicrographs. It presents a simple test for differentiating between worthless and useful "nitrosolvents" and also discusses the 1 Published by permission of the director of the U. S. Bureau of Mines. SCIENTIFIC BOOKS An Introduction to Entomology. By JOHN HENRY COMSTOCK, Professor of Entomology and General Invertebrate Zoology, Emeritus, in Cornell University. Ithaca, N. Y., Comstock Publishing Company. 1920, xviii+ 220 pages, 220 figs. The dean of American entomologists has just issued the first part of a second edition, entirely rewritten, of his long-known text-book called "An Introduction to Entomology." It covers the structure and metamorphosis of insects, and it covers these subjects in such complete and thoroughgoing way and, at the same time, in such compact manner, as to make the book by all odds the very best of extant texts to put into the hands of entomological and zoological students. It will be indispensable for beginning students; it will be very useful for advanced ones. Such large compendiums as Berlese's (as yet only available in the original Italian), and Sharp's (in the English "Cambridge Natural History") and Packard's "Text-book of Entomology," are all of a character which limits their use in the laboratory to that of reference books; they are too extended and expensive, to say nothing of their less adapted organization and general make-up, to permit their use as actual individual laboratory handbooks. Comstock's book fills exactly the long-felt need. It contains all the knowledge up to the very present, carefully analyzed, sifted, and a great part of it actually contributed or tested by Comstock and his students, that the general student of insect structure and post-embryonic development needs to know. And it is all packed away, in perfect arrangement, with elaborate analytical contents, sufficient index and bibliography and carefully chosen illustrations, in about two 2 Chemist, Pittsburgh Experiment Station, Bureau of Mines. hundred pages, clearly printed on good paper, and substantially bound in convenient format. The experience of a veteran text-book maker and user shows in every feature of this book's construction. The new book is "affectionately inscribed" to the author's "old students whose youthful enthusiasm was a constant inspiration" during a long period of service as teacher, as an effort to further aid them, though they are now gone from his classrooms and laboratories. Professor Comstock may rest assured that his greeting will be quite as affectionately returned, and that his latest effort will be as gratefully received by his many scattered students, mostly now no longer youthful, as were his earlier efforts to instil in them that love of nature and passionate interest in learning to know nature's works which have been for so many years beautifully characteristic of their beloved mentor. These old students will be greatly helped by this effort in their attempts to carry on to new students the Comstock tradition. And American entomology has not had, nor will ever have, any finer tradition. VERNON KELLOGG SPECIAL ARTICLES "PHYSICAL CONSTANTS PERTAINING TO THE OCEAN AN important object of the science of physics is description of the behavior of different substances. Expression in mathe matical form of such descriptions requires the use of one or more 66 physical constants," such as the coefficient of elasticity, conduotivity, etc. Constants thus obtained are generally regarded as intrinsic, or peculiar to the substance. The extensive list of "physical constants" already determined bears witness to the achievements of physics, and constitutes fundamental quantitative data of the science. Application of the methods of physics to terrestrial phenomena taking place on a correspondingly immense scale, has likewise resulted in physical laws or descriptions capable of expression in mathematical form. But the corresponding "physical constants" can not be evaluated by means of experiments necessarily limited to much smaller dimensions. The influence of the enormous magnitudes involved in many terrestrial phenomena can be determined only by observing the phenomena as they take place in nature. It is impossible, for example, to determine in detail the motion of the water particles in the convective circulation of even a limited part of the sea. But this would be necessary in order to resolve the water mass into sufficiently small portions to justify the assumption, made in laboratory experiments, of flow in plane layers. Even if this resolution of the complex motion into its elements were possible, there would still be the impracticable task of summing up the effects of the correspondingly complex and irregular system of forces in order to obtain the resultant effect. The only recourse is to observe the system as a whole under the actual conditions of the sea. For example, a decade ago, the Swedish physicist, V. W. Ekman, applied the classical hydrodynamical equations to certain ocean current observations, but replaced the viscosity coefficient by a constant representing the integrated effect of the complex system of frictional forces. The value of this constant is thousands of times greater than the coeffi cient of viscosity of sea-water. A generation ago, a German mathematician, Zöppritz, developed an elaborate mathematical theory of ocean currents, but used laboratory values of the physical constants. Consequently his theory disagreed widely with subsequent objective knowledge. Such results emphasize the fact that physical constants are dependent not only upon the nature of the substances, but also upon the corresponding external conditions, and must therefore be determined under the conditions prevailing where they are to be used. Progress in laboratory investigations is continually demonstrating the variability of quantities originally regarded as physical constants. Further refinement often requires the substitution of a variable, dependent upon additional conditions, for constant quantities of earlier formulæ. This is also true in cosmic and terrestrial physics. Continuous and highly refined observations on the sun have demonstrated the variable nature of the "solar constant." The so-called constants of heat conductivity, diffusion, viscosity, etc., pertaining to the ocean also vary with the conditions, though they are all thousands of times larger than the corresponding laboratory values. For example, to determine the upwelling velocity in the southern California coastal region the author applied the classical equation1 for the diffusion of salts in a medium moving with the velocity W, to seasonal observations of ocean salinities at a series of depths, and obtained the value 40 in C.G.S. units for the diffusion constant u2, while a Norwegian investigator, Jacobsen, obtained values varying from 0.3 to 11.4 for different regions of the sea near Denmark. The laboratory value for the diffusion coefficient of ocean salts in water is only .0000125. The upwelling velocity in the southern California region was also determined by applying to serial ocean temperatures Fourier's equation for the flow of heat in a moving medium. The conductivity constant for this ocean region was found to be 30, while the laboratory value of the coefficient of conductivity of sea-water is only .0012. The values of such constants found under the simple conditions of laboratory control are known to depend upon the temperature of the fluid. This is in turn an index of the complex molecular activity. In the ocean, the corresponding variable factor is the rate of interchange of small parts of the water in the ever present alternating convective circulation. Complicated as those phenomena are, encouraging results have already come from quantitative studies, not only in oceanog 1 Ocean temperatures, their relation to solar radiation: quantitative comparisons of certain empirical results with those deduced by principles and methods of mathematical physics by George F. McEwen, 1919, Semicentennial Publications of the University of California, 1868-1918, pp. 336-421, 19 figs. in text. raphy, but also in other geophysical investigations. GEORGE F. MCEWEN SCRIPPS INSTITUTION FOR BIOLOGICAL RESEARCH, UNIVERSITY OF CALIFORNIA THE DIFFERENTIAL STAINING OF PLANT PATHOGEN AND HOST THE well-known difficulty experienced in staining to differentiate pathogen from host tissues in phytopathological studies needs no comment. In order to obviate this difficulty the writer has tried numerous combinations of stains and finally a method was hit upon which gives uniformly satisfactory results from the histological point of view. It is not intended for cytological studies although even for these there may be possibilities in the method. The comparatively short time required to complete preparations, and the fact that students not yet expert in microtechnique can in most cases obtain good mounts, decided the question of publication. 2. Wash in 95 per cent. and 85 per cent. alcohols. 3. Stain with Magdala red 5 to 10 minutes. 4. Remove surplus stain and wash in 95 per cent. alcohol. 5. Stain with Licht grün in clove oil for 1 to 3 minutes. 6. Wash in absolute alcohol, or in carbol-turpentine. 7. Clear in xylol and mount in Canada balsam. The time factors may require slight modifications in some cases but a microscopic examination of the slide will enable the worker easily to determine the variation required. As a rule the staining with Licht grün is very rapid and if overstaining occurs the red becomes tinged with purple although this may |