two sharp fringes make it possible to utilize them even in cases when the auxiliary mirrors vibrate. The vibration interferometer is quite sensitive, provided the average currents are of the order of several microamperes. On the Essence of Physical Relativity: Sir Joseph Larmor, Cambridge, England. A general discussion of the physics underlying relativity, with particular reference to an article by Leigh Page. Gravitational Attraction in Connection with the Rectangular Interferometer: Carl Barus, Department of Physics, Brown University. The rectangular interferometer is so sensitive in the measurement of small angles that it may be used for the measurement of the Newtonian constant of gravitational attraction. The General Character of Specific Heats at High Temperatures: Walter P. White, Geophysical Laboratory, Carnegie Institution of Washington. The general law covering the behavior of atomic heats from the lowest temperatures up demands that at sufficiently high temperatures all atomic heats at constant volumes should have the value 5.96. A contrary hypothesis has been made, namely, that atomic heats continue to increase with the temperature. The substances here examined give evidence that the atomic heats do increase above the value 5.96. On Certain Projective Generalizations of Metric Theorems, and the Curves of Darboux and Segre: Gabriel M. Green, Department of Mathematics, Harvard University. The continuation of earlier work by the same author in the Proceedings. The Rectangular Interferometer with Achromatic Displacement Fringes in Connection with the Horizontal Pendulum: Carl Barus, Department of Physics, Brown University. THE twelfth number of Volume 4 contains the following articles: The Absorption Spectrum of the Novae: W. S. Adams, Mount Wilson Observatory, Carnegie Institution of Washington. A discussion of Nova Aurige of 1892, Nova Persei of 1901, Nova Geminorum of 1912, and Nova Aquilæ of 1918. The displacements of the lines in all these stars are directly proportional to wavelengths, and divide themselves into two pairs of equal amount. Of these the first pair of stars has exactly twice the displacement of the second. In the case of Nova Aquile, there is a progressive increase in the values of the displacements of the absorption lines at successive dates. Various hypothetical explanations are discussed. On Jacobi's Extension of the Continental Fraction Algorithm: D. N. Lehmer, Department of Mathematics, University of California. A closer study of Jacobi's expansion reveals a number of remarkable points. Six theorems are stated. A Characterization of Jordan Regions by Properties having no no reference to their Boundaries: Robert L. Moore, Department of Mathematics, University of Pennsylvania. The theorem is proved: In order that a simply connected, limited, two-dimensional domain R should have a simple closed curve as its boundary it is necessary and sufficient that R should be uniformly connected im kleinen. A Biometric Study of Human Basal Metabolism: J. Arthur Harris and Francis G. Benedict, Nutrition Laboratory and Station for Experimental Evolution, Carnegie Institution of Washington. An analysis of measurements on 136 men, 103 women, and 94 new-born infants. Sex and Sex Intergrades in Cladocera: Arthur M. Banta, Station for Experimental Evolution, Carnegie Institution of Washington. The presentation of facts in regard to Cladocera, with the discussion of their significance with regard to sex intergrades in general, leading to the tentative conclusion that sex is always relative and that while most individuals of whatever species are prevailingly male or prevailingly female, every individual may have something of the other sex intermingled with its prevailing sexual characters. On the Method of Progression in Polyclads: W. J. Crozier, Bermuda Biological Station for Research, Dyer Island, Bermuda. In turbellarians generally, muscular operations analogous to those executed by the foot of chitons and of gastropods are essentially concerned in creeping locomotion. The Phylogeny of the Acorn Barnacles: Rudolf Ruedemann, State Museum, Albany, N. Y. The derivation of an Eobalanus from a Rhinocaris-like phyllopod is illustrated in a set of diagrams. Possible Derivation of the Lepadid Barnacles from the Phyllopods: John M. Clarke, State Museum, Albany, N. Y. So far as present knowledge extends, the metamorphoses of the phyllopods into the two great branches of the barnacles were essentially contemporaneous. Refractive Index and Solubilities of the Nitrates of Lead Isotopes: Theodore W. Richards and Walter C. Schumb, Wolcott Gibbs Memorial Laboratory, Harvard University. The difference in atomic weight of the lead (207.20 and 206.41) has no appreciable effect on the refractive index or on the molal solubility of the different samples of lead nitrate. The Purification by Sublimation and the Analysis of Gallium Chloride: Theodore W. Richards, W. M. Craig and J. Sameshima. Wolcott Gibbs Memorial Laboratory, Harvard University. The method rests on the fact that gallium trichloride sublimes and distils at a low temperature, whereas the other chlorides likely to be associated with it are much less volatile. The Purification of Gallium by Electrolysis, and the Compressibility and Density of Gallium: Theodore W. Richards and Sylvester Boyer, Wolcott Gibbs Memorial Laboratory, Harvard University. The method of separating gallium from indium by means of the different solubilities of the hydroxides in caustic alkali was tested without success; much more promising results were obtained by the electrolytic method. The compressibility of solid gallium was found to be 2.09 X 10-, and of liquid gallium 3.97 X 10-, nearly twice as great, although its volume is less. The density of the liquid was 6.081, and of the solid 5.885. The Growth-rate of Samoan Coral Reefs: Alfred G. Mayor, Department of Marine Biology, Carnegie Institution of Washington. the growth rate of Acropora, Porites, Pocillopra, Pavona, Psammocora are given; and the weight of limestone added per year to the upper surface of the Aua reef-flat is estimated as 805,000 lbs. Other similar estimates are given. The Distances of Six Planetary Nebula: Adriaan van Maanen, Mt. Wilson Solar Observatory, Carnegie Institution of Washington. The nebula N.G.C. 2392, 6720, 6804, 6905, 7008 and 7662 are examined. The parallaxes range from 0."002 to 0."021, and the diameters from 10,000 to 1,350 astronomical units. National Research Council: Minutes of the Meeting of the Executive Board, July 9, August 13, September 9 and October 8. We may summarize the articles in Volume 4 of the Proceedings as follows: Mathematics, 9; Astronomy, 11; Physics and Engineering, 25; Chemistry, 5; Geology and Paleontology, including Mineralogy and Petrology, 9; Botany, 3 (see also Genetics); Zoology, including General Biology, 12 (see also Genetics); Genetics, 6; Physiology and Pathology, 10; Anthropology and Psychology, 1; a total of 91 articles. The division of these articles between members of the Academy and non-members is 39 and 52 respectively. The list of institutions which have contributed three or more articles is as follows: Carnegie Institution, 15, divided as follows: Solar Observatory, 7, Nutrition Laboratory, 4, Geophysical Laboratory, 1, Marine Biology, 1, Station for Experimental Evolution, 1, Tortugas Laboratory, 1; Harvard University, 15; Brown University, 7; University of Illinois, 5; Bermuda Biological Station for Research, 4; University of California, 4; University of Chicago, 4; University of Pennsylvania, 4. EDWIN BIDWELL WILSON MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE, Mass. SPECIAL ARTICLES OPPORTUNITIES FOR CONTACT INFECTION1 AN outstanding feature of the influenza pandemic is the remarkable infectivity of the disease. There is scarcely a community in 1 Published by permission of the Surgeon-General of the Army. this country that has escaped its visitation. Once introduced it has spread from person to person with truly amazing speed. This is partially accounted for by the very short incubation period, from two or four days. This furnishes new foci of infection at a much more rapid rate than is the case with certain other infectious diseases which require from five to twenty days to develop. So much for the progress of the disease, once rooted in the individual, but just how the infection is passed about so widely is a matter that is less easy to explain. Are the causative organisms transmitted from person to person by contact, or are they mixed with dust from salivaladen streets and scattered broadcast by the wind? The trend of modern thought is to regard contact or hand to mouth transmission as by far the more important. It is only at such times as we have just experienced that there is a tendency to question the adequacy of this method. Dust holds out certain allurements because of its ubiquity and there is just enough of the mysterious associated with airborne infection to be in keeping with a disease about which we know so little. Lest we wander too far from the truths which modern public health experience has taught us the following inventory of opportunities for contact transmision of disease is offered. The writer recorded his chances of acquiring infections for an entire day. This list undoubtedly is typical for the average city dweller. For the purpose of emphasis the items are recorded in detail: 1. Touched bathroom doorknob. 2. Touched toilet seat. 3. Touched toilet flush handle. 4. Touched chain on light. 5. Touched faucet handle. (Washed hands.) 6. Touched bathroom doorknob. 7. Touched knob of outside door. 8. Received paper from newsboy. 9. Grasped handle of trolley car. 10. Received transfer from conductor. (Gloves on hands from this time till entering restaurant.) 11. Grasped back of chair in restaurant. 12. Touched tumbler with hand. 13. Touched tumbler with lips. 14. Touched teaspoon with hand. 25. Touched shredded wheat with hand. 31. Wiped mouth with napkin. 34. Received change from cashier. 36. Closed door. (Put on gloves.) 42. Touched swinging doors on toilet. 43. Touched toilet room door knob. 53. Opened lunchroom door. (Washed (Washed hands.) 54, 55, 56. Received three dishes from attendant. 57. Handled chair. 58. Handled water tumbler. 59. Carried glass to lips. 60. Put spoon in mouth. 61. Put fork in mouth. 62. Opened post office door. 63. Licked postage stamp handed out by clerk. 64. Opened post office door. 65. Opened office door. 66. Placed hand on rail. 67. Opened office door. 68. Grasped handle on trolley car. 69. Opened door of bank. 70. Grasped pen used by public. 71. Received bills from cashier. 72. Opened bank door. 73. Opened toilet room door. 74. Closed swinging doors. 75. Touched flush handle. 76. Opened swinging doors. 77. Touched faucet. (Washed hands.) 78. Opened toilet room door. 79. Pressed handle on drinking fountain with hand. 80. Handled toilet room door. 81. Pressed toilet flush. 82. Turned faucet handle. (Washed hands.) 83. Opened toilet room door. 84. Received newspaper. 85. Received change from newsboy. 0 ..... ing of others Chances of acquiring infection through kissing. 0 There were 92 opportunities for infecting the hands directly with other hands or with articles just handled by others. Mere infection of the hands is of course immaterial. It is the carrying of the infected hand to the mouth or nose, which constitutes the danger. In the present instance the hand was brought in contact with the mouth or nose, either directly or through food, or through handling a handkerchief 14 times, 7 times in the case of the mouth and 7 in the case of the nose. This represents the experience of one to whom keeping hands out of the mouth is second nature. But what of the person who is unconscious of the hand to mouth habit? There is no question but that the hand travels to the mouth more frequently with the average individual. There were seven opportunities of infecting the nose with the hand through the medium of the handkerchief. The influence of weather and climate on infection is suggested here by the fact that the colder or more changeable the weather the more frequently does the nose require attention and the opportunities for infecting the nose from the hand increase in proportion. In making up this record of articles touched by the hands, it should be emphasized that only those instances have been recorded which offered the possibility of infection through recent handling of the article by others. Contact with papers, pencils, etc., handled remotely by others have not been included. Another point that stands forth is that our hands are dangerous to others only in proportion to the frequency with which we infect them with our mouth and nose. The present experience shows seven hand-to-nose contacts and but two direct hand-to-mouth contacts. The handkerchief thus looms up as a factor of importance. Through it we may infect our hands from our nose, which is dangerous to others, and also infect our nose with our hands which is dangerous to ourselves. Several lessons of practical value suggest themselves from the above related experience. They are: I. That we should use handkerchiefs one side of which is conspicuously colored or marked so that we may always apply the hands to one side reserving the other side for the nose. This will protect our own nose from our hands and help to prevent the infection of our hands. II. That we should abandon the universal practise of shaking hands, substituting some other less intimate method of salutation. III. That we should encourage means which will lessen the opportunity for public restaurant employees to handle eating utensils. GEORGE T. PALMER, Captain, Sanitary Corps, U. S. A. A PRELIMINARY NOTE ON A BACTERIAL DISEASE OF FOXTAIL DURING the month of September and up until the middle of November, 1918, a striking disease on foxtail (Setaria glauca (L.) Beauv.) was noticeable around Fayetteville, Ark. The disease was rather widespread in this vicinity and it is quite probable that it is prevalent throughout the state of Arkansas at least. The disease manifests itself as dark brown spots and streaks, varying in size from small, oval or roundish spots, 1-2 mm. in diameter, to elongated streaks, 2-3 cm. in length. The attacked areas are to be found on leaves, flowering stalks and glumes. The pathogen, a white, rod-shaped bacterium was isolated and obtained in pure culture. It was inoculated on healthy leaves by using a sterile, platinum needle and smearing the organism on the leaf. Within three to four days inoculated spots showed the characteristic browning of the tissue. The organism was then reisolated and obtained in pure culture from the inoculated spots. 1 Both by spraying and by needle smears this organism was successfully inoculated on wheat, oats, rye, barley, corn and Sudan grass; it was reisolated and obtained in pure culture from each of the above-named hosts. Infections were also obtained on sorghum and millet but no reisolations have been obtained from these up to the time of writing. Judging from the appearance of infected plants in the greenhouse all the cereals mentioned, except corn and the various grasses of the Sorghum group, are quite seriously attacked. The effect on oats is not unlike the halo blight recently described by Miss Elliott2 and it is likely that the organisms under discussion is the same as Mann's Pseudomonas avena. However, the identity of the organism is still in doubt and the work is being continued. H. H. ROSEN AGRICULTURAL EXPERIMENT STATION, UNIVERSITY OF ARKANSAS THE AMERICAN METRIC ASSOCIATION THE following is a summary of the proceedings of the second annual meeting of the American Metric Association (156 Fifth Avenue, New York City), held in Baltimore on December 27 and in Washington on December 28. Mr. David A. Molitor, consulting engineer, outlined his work for the C. E. Schmidt Co., of Detroit, tanners. He found that about 500 different commodities were being purchased for the use of this company and that they were received in many different units of weight and measure. It became clear that economy would be effected by entering the weight or measure of all material received in 1 Since this article was written the organism has also been reisolated from these hosts. 2 Elliott, C., "Bacterial Oat Blight," Phytopath. 8: 489, 1918. 3 Manns, T. F., "The Blade Blight of Oats," Ohio Agri. Exp. Sta. Bul. 210, 1909. |