three months' tour. His principal object is to consult the British Museum and other libraries in connection with his study of the history of American medicinal plants and drugs.

AT the Montana College and Experiment Station. President A. Atkinson has been granted leave of absence for study during the next college year. Dean and Director F. B. Linfield has been appointed acting president in his absence. Dr. Arnold H. Johnson, assistant chemist in the station, has also been granted leave of absence for one year to accept a fellowship for study in Europe given by the International Education Board.

FORESTERS and chemists from England, Australia, Sweden, Finland and Mexico, detailed recently to the U. S. Forest Products Laboratory of the University of Wisconsin, constitute the largest group of foreign research men ever gathered at the federal laboratory at one time. Included in the foreign research group are Wilhelm Rosen and Eric Ostlin, of the Scandinavian-American Foundation; J. E. Cummins and H. S. Dadswell, of the Australian Council for Scientific and Industrial Research; W. G. Campbell, of the Commonwealth (British) Foundation; Hermenegildo Barrios, of Mexico, and Uno W. Lehtinen, of the Finnish State Forest Service.

DR. HARRISON R. HUNT, head of the department of zoology and geology at the Michigan State College, is making a lecture tour through the west in the interests of the American Eugenics Society. He planned to lecture on eugenics and human heredity at the University of Omaha, Oregon State Normal School, State Normal School at Bellingham, Washington, and the State Normal School at Ellensburg, Washington.

DR. JACK CECIL DRUMMOND, professor of biochemistry in University College, London, vice-dean of the faculty of medical science, is among those lecturing at the American Chemical Society Institute at the Pennsylvania State College.

THE death is announced on May 15 of Dr. Edwin B. Payson, professor of botany in the University of Wyoming.

UNIVERSITY AND EDUCATIONAL
NOTES

YALE UNIVERSITY has received a bequest of more than $150,000 from the estate of General Charles H. Pine, formerly of Ansonia, which, together with a gift of General Pine's made in 1913, brings the Charles H. Pine scholarship fund at Yale to a total of more than $215,000.

AT the commencement exercises of the University of Maryland gifts were announced amounting to $150,000. The largest gift was from Captain Isaac E. Emerson, of Baltimore, who provided endowment for a professorship in the school of pharmacy and a fellowship in the school of medicine. The University of Maryland during the coming biennium will have almost $1,000,000 for new buildings and improvements from the state.

THE University of London has received two gifts of £10,000 each, one from an anonymous donor and one from Messrs. Wander, Ltd., for the establishment of a university chair of dietetics.

It is announced at Columbia University that Dr. Durward R. Jones, recently epidemiologist of the State Department of Health of South Dakota, will succeed Dr. Alton S. Pope as assistant professor of epidemiology, and that Dr. Adelaide Ross Smith, recently physician to the New York State Industrial Board, will succeed Assistant Professor Frank G. Pedley as associate professor of medicine in industrial hygiene. Dr. Smith will be in charge of the industrial department at the Vanderbilt Clinic of the College of Physicians and Surgeons. Dr. Pope is now epidemiologist of the Chicago Health Department, and Dr. Pedley will assume charge of the new department of industrial medicine at McGill University Medical School on August 1.

ERIC PONDER, M.D., Sc.D., F.R.S., of Edinburgh, has been appointed associate professor of general physiology in New York University and will have charge of the courses in physiology in University College. He will also direct work in general physiology in the graduate school.

DR. HERBERT O. CALVERY, instructor in physiological chemistry at the Johns Hopkins Medical School, has been appointed assistant professor of physiological chemistry at the University of Michigan.

DR. D. A. WORCESTER has been appointed associate professor of educational psychology in the University of Nebraska.

DR. N. B. DREYER, assistant professor of physiology, Dalhousie University Faculty of Medicine, has resigned to accept an appointment in the department of pharmacology at McGill University Faculty of Medicine, Montreal.

DISCUSSION

MISUSE OF THE NAME "LEUCOSCOPE" I ASK the privilege of your columns in order to clarify a somewhat confused account of some work

of mine given in Walsh's "Photometry," pp. 244–245. Since the same mistake has also been made by others heretofore and bids fair to become prevalent, it seems desirable to publish a correction. I do this not for the sake of finding fault, but to prevent in so far as possible, the continued spread of mistaken ideas in regard to the subject-matter in question. It is well known how errors once incorporated in a standard text are copied and recopied without limit.

The error in question is that the instrument designated by Mr. Walsh as "The Leucoscope" is not the leucoscope, but the "rotary dispersion colorimetric photometer." The pertinent facts are as follows:

(1) The leucoscope is an instrument, the invention of which is commonly attributed to Helmholtz, about 1870-80.2 It consists essentially of a quartz plate between a Wollaston prism and a nicol prism through which the observer views two images of the

same source.

(2) The instrument which Mr. Walsh describes, and calls "The Leucoscope" is properly called the "rotatory dispersion colorimetric photometer." I particularly object to naming it "Priest's leucoscope" as is done in the index of Mr. Walsh's book. It is a special form of the Arons Chromoscope and its embryonic form may be seen in Zoellner's colorimeter. My connection with this instrument has been to develop the theory and practice of its use in the colorimetry and photometry of incandescent sources and daylight, and to design an instrument especially suited to these purposes.

(3) In principle, manner of use and specific purpose served, the two instruments are very different. About all that they have in common is the fact that they both contain nicol prisms and quartz plates and the circumstance that I have written papers dealing with each of them separately.

It seems unnecessary to use your space to set forth in detail the distinctions between these two instruments. All confusion may be removed by consulting 1 J. W. T. Walsh, "Photometry," Constable, London,

1926.

2 There has been some slight controversy as to the relative contributions of Helmholtz, and one of his pupils, Diro Kitao, to the development of the instrument. Edm. Rose (1863) described an instrument which may be regarded as the prototype of the leucoscope. A review of the history of the instrument and a full bibliography have been published in my paper on the leucoscope, Jour. Op. Soc. Am. 4, pp. 448-495, 1920.

3 J. O. S. A. § R. S. I. 7, folded insert facing p. 1199, December, 1923.

4 Leo Arons, Ann. der Phy. (4) 39, pp. 545-568, 1912. J. C. F. Zoellner, "Photometrie des Himmels," Berlin, 1861; G. Mueller, "Photometrie der Gestirne," pp. 244-254, Leipzig, 1897.

my papers which deal, respectively, with the two different instruments." IRWIN G. PRIEST

TADPOLES AS A SOURCE OF PROTOZOA FOR CLASSROOM USE

IN SCIENCE, Vol. 56, pp. 439-441, there appeared a note by Dr. R. W. Hegner on frog and toad tadpoles as sources of intestinal protozoa for teaching purposes. During the last four years the writer has examined hundreds of tadpoles for intestinal protozoa, and is able to state that he has frequently found most of the species listed by Hegner in his paper, viz., Trichomonas augusta, Hexamitus intestinalis, Nyctotherus cordiformis, Opalina ranarum, Endamoeba ranarum, and Euglenamorpha hegneri, the latter an Euglena-like flagellate with three flagella. Giardia agilis and Balantidium entozoon have never been observed by the writer. Euglena spirogyra, Phacus sp. and several species of desmids and diatoms, which are normally free-living forms, are often present in large numbers in the rectum of tadpoles, in which habitat they appear to be little the worse for any contact they may have had with the digestive juices of their host.

In addition to the protozoa enumerated by Hegner several other species have been more or less frequently encountered. These are Chilomastix caulleryi Alexeieff 1909, Mastigina hylae (Frenzel 1892) Goldschmidt 1907, and Endolimax ranarum Epstein and Ilowaisky 1914.

Chilomastix caulleryi is a flagellate which lives in the rectum of the tadpoles of Rana catesbiana and Rana clamata. It sometimes occurs, in large numbers, but is likely to be overlooked among the more numerous representatives of the species Trichomonas augusta. Its morphology is practically identical with that of Chilomastix mesnili of man. Its larger size makes it more favorable for study than the human form.

Mastigina hylae is a large and extremely interesting protozoon which belongs to the flagellate family Rhizomastigidae. Its most striking features are the prominent anterior nucleus and the constant active streaming of the protoplasm filled with remnants of the green algae and protozoa upon which it has fed. The small anterior flagellum is inconspicuous and will be overlooked unless carefully searched for. The writer has never seen in any other cell protoplasmic streaming so vigorous and continuous as in this form. For a more detailed description of this species the reader is referred to a paper by the writer in the

"A New Study of the Leucoscope. . .," J. O. S. A. 4, pp. 448-495, November, 1920; "Colorimetry and Photometry by the Method of Rotatory Dispersion," J. O. S. A. & R. S. I. 7, pp. 1175-1209, December, 1923.

...

Journal of Parasitology for June, 1925. This protozoon has been found in tadpoles of Rana catesbiana and R. clamata in New Jersey and in those of R. pipiens in Iowa.

Endolimax ranarum is a smaller amoeba than Endamoeba ranarum, and is much less frequently encountered. Its nucleus is more or less typical of that of other members of the genus and careful staining is required to bring it out.

On the basis of the combined experiences of Dr. Hegner and those of the writer, we may confidently expect to find in our American tadpoles most of the following species of intestinal protozoa: (1) Opalina ranarum, (2) Nyctotherus cordiformis, (3) Balantidium entozoon (not observed by either Hegner or the writer), (4) Giardi agilis, (5) Trichomonas augusta, (6) Chilomastix caulleryi, (7) Hexamitus intestinalis, (8) Euglenamorpha hegneri, (9) Mastigina hylae, (10) Endamoeba ranarum, and (11) Endolimax ranarum. Trichomonas batrachorum and Polymastix bufonis are two other species which have been found in frogs and should be searched for in tadpoles. This formidable list of intestinal protozoa makes tadpoles invaluable for teachers in protozoology and invertebrate zoology.

The writer wishes also to call the attention of bacteriologists and microbiologists to a rather unusual bacterial flora which is sometimes encountered in the rectum of the tadpole. Large spirilla with a prominent spore at each end, bacilli of a crescentic shape with a prominent spore at each end, and other equally remarkable forms have been seen by the writer while making examinations of the contents of the rectum of tadpoles.

IOWA STATE COLLEGE

ELERY R. BECKER

THE EFFECT OF ULTRAVIOLET RADIATIONS UPON SOY BEANS

A SERIES of experiments was performed to study the effect of ultraviolet radiations upon the subsequent development of the soy bean. The full spectrum of an air-cooled quartz mercury lamp was used in every case. The plants were kept under rigidly controlled conditions.

The first outstanding result noted was that the longer the exposure the shorter the plant, that is, in successive experiments as the length of exposure was increased the internodes of the plant became shorter. The stems were very brittle and the leaf tissue very stiff and rigid.

The internal changes were equally interesting. The stems of irradiated plants were approximately one and one half times as large in diameter as the control plants. There was also a reduction of the number of medullary rays in irradiated plants, so

that these plants tend to show that the meristematic tissues remain active for a very much longer period of time than in the control plants. The cells of the medullary rays under ordinary conditions remain parenchymatous but in irradiated plants have gone further and developed into xylem and phloem. Furthermore, because of differential growth the stems became hollow.

A detailed report of the work will be prepared later. The author wishes to express her appreciation to Dr. W. J. G. Land and Dr. C. A. Shull for their kind help and inspiration.

UNIVERSITY OF CHICAGO

H. REBECCA DANE

FLORA OF BARRO COLORADO ISLAND, CANAL ZONE

RECENTLY there appeared in SCIENCE an account of Barro Colorado Island.1 Visiting scientists working upon plants are concerned with the names of the species to be found on the island. All such workers will be interested in a list of plants of Barro Colorado Island that has just been issued by the Smithsonian Institution. The author, Mr. Paul C. Standley,2 who spent a week on the island, has traveled extensively in Central America and has published several articles on the flora of these regions. The flora is an annotated list without keys or complete descriptions, but the accompanying notes on common names, uses and prominent characters will be a great aid to those taking advantage of the facilities of the laboratory on the island.

Mr. Standley has also published a paper on the ferns of the island. A flora of the Canal Zone by the same author is now in press.

The bibliography of papers relating to Barro Colorado Island now includes over 50 titles.

BUREAU OF PLANT INDUSTRY, WASHINGTON, D. C.

A. S. HITCHCOCK

A DAYLIGHT METEOR

AT a golf course on Warwick Neck, near Providence, Rhode Island, I was on a fairway overlooking Narragansett Bay about one o'clock in the afternoon of June 1, in brilliant sunlight when my companion and I distinctly saw what seemed to be a small meteorite dropping over the bay. It was fol

1 Kellogg, Vernon, "Barro Colorado Island Biological Station," SCIENCE 65: 535, 1927.

2 Standley, Paul C., "The Flora of Barro Colorado Island, Panama," Smithsonian Miscellaneous Collections 78: No. 8, 1-32, 1927.

3 Standley, Paul C., "The Ferns of Barro Colorado Island," American Fern Journal 16: 112-120, 1926; 17: 1-8, 1927.

IN 1924 the Federal Parliament of Australia, knowing the fact that the unique native fauna of the commonwealth was fast disappearing, and recognizing its importance to medical science, founded the National Museum of Australian Zoology. It was a -wise and statesmanlike act, the full effect of which is only now beginning to be seen. Dr. Colin Mackenzie was appointed director, with the title of professor of comparative anatomy. It was a museum with a difference. In the previous year Professor Mackenzie had presented to the commonwealth his specimens of iving native animals, together with the buildings and fencing on the Research Reservation at Healesville. He had given also his collection of macroscopic and nieroscopic specimens, numbering many thousands; and these now form the basis of the museum collecion. Each specimen has a direct application to ome medical or surgical problem. Nothing quite ike the collection of normal histological preparations rom reptiles, monotremes and marsupials, with rhich human or other mammalian tissue can be comared, exists anywhere in the world, and we are glad o know that illustrated atlases describing the collecion are being prepared for publication-a huge enterrise which has been begun not a day too soon. Early ↑ 1923, when commenting on the announcement that he commonwealth government had passed an act to stablish a Museum of Australian Zoology, we oberved that there was clearly an obligation on Ausalia to preserve a full series of specimens, since the hole indigenous fauna of Australia seemed only too kely to follow Tasmanian man to extinction. The mmonwealth legislature has now gone rather furer than we hoped, for it has not only allotted a site r the National Museum of Australian Zoology at anberra, the new capital of Australia, but the Fedal Capital Commission has provided a site for a ological park or reservation, in which will be kept ring specimens of Australian and Tasmanian native imals in their natural state. The area of the site r the museum, laboratories and lecture theater is

about five and a half acres, in a magnificent situation on Action Hill, facing Parliament House. The research reservation or zoological park, containing about eighty acres, is on a peninsula bounded on two sides by the river Molonglo. The report of the Parliamentary Standing Committee on Public Works, dealing with the construction of buildings, has now been published, authorizing for this purpose a sum approximating £100,000. The report has received the unanimous approval of the Federal Parliament, and the buildings, representing what is really the first stage in the establishment of the National University of Australia, will be begun immediately. When the buildings are completed every facility will be offered to workers-not only Australian, but also from other countries-wishing to study comparative anatomy and its application to modern medical and surgical practice. The museum is now at Melbourne, but is to be moved to Canberra next year. To its original contents many important additions have recently been made, including the collection of specimens valued at £25,000 belonging to Dr. George Horne, of Melbourne, dealing with the Stone Age men of Australia, and also a collection of aboriginal skulls made by Dr. Arthur Nankivell, of Kerang. The museum also possesses the Froggatt entomological collection, and that of Mr. Murray Black dealing with the aborigines of South-East Victoria. The completely fossilized prehistoric Cohuna skull, together with many other specimens of anthropological value, belong to the museum. The federal government of Australia is to be congratulated on its decision to establish a center for the advancement of comparative anatomy, which admittedly is the foundation of all the medical sciences. We may venture to express the hope that the lead now given by Professor Colin Mackenzie will encourage wealthy Australians to display a similar national spirit, and by liberal endowments help on the necessary research work in the interests of humanity.-The British Medical Journal.

SCIENTIFIC BOOKS

The Internal Constitution of the Stars. By A. S. EDDINGTON, M.A., F.R.S., Cambridge; at the University Press, 1926. 407 pp., 5 figures.

THE fundamental problem in astrophysics may be regarded as the construction of models which, obeying the well-established laws of theoretical physics, describe the observed intrinsic properties of the stars. Thus there are stellar models which describe the formation of the observed spectra in reversing layer and chromosphere, models which describe the formation of binary stars by fission and the behavior of cepheid

variables and finally models which lead to relations between the mass, radius, luminosity and effective temperature of a star. Such stellar models, both as regards their field of usefulness in scientific thought as well as their frequent incompatibility with one another, are closely analogous to the various atomic models designed to describe the properties of matter. In astronomy, as well as in atomic physics, the value of a given model depends upon the range of facts quantitatively described, upon its powers of prediction and upon the small number of special postulates built into the model.

It is now some ten years since the appearance of Eddington's first paper on the interior of a star. The general theory therein developed and the model adopted furnished a successful description of the stars as then known. The development by Kramers, from the correspondence principle, of an expression for the mass coefficient of absorption permitted Eddington in 1924 greatly to improve his model and to predict the mass-luminosity relation. This prediction and its verification have profoundly modified astronomical conceptions of stellar evolution. At the same time, Eddington's theory has reacted upon modern. atomic physics and has inspired numerous important investigations on the physics of matter at high temperatures, notably the work of Eggert (which led to Saha's important theory) and the recent investigations of R. H. Fowler. Astronomers and physicists both, then, will welcome the present volume in which Eddington gives a systematic development of the whole theory.

The general treatment may be outlined in the following manner: Given a mass of gas under its own gravitational attraction, the internal distribution of density, pressure and temperature may be derived from the equation of state of the gas and the requirements of mechanical and thermal equilibrium. The condition of mechanical equilibrium requires that the total pressure (gas pressure + radiation pressure) at any internal point balances the weight of the overlying layers, and is expressed by the wellknown differential equation of hydrostatics. The condition of thermal equilibrium requires that the flow of heat does not disturb the internal distribution of temperature, but to formulate the differential equation it is necessary to know the mode of heat transfer. Schwarzschild has shown that this transfer in the outer layers of the sun is by radiation rather than convection, and Eddington has shown that convection currents can in fact be only maintained at the expense of their own mechanical energy and so must die out. Granting that heat transfer is by radiation, the well-known differential equation of radiative equilibrium may be derived from elementary consid

erations, and this equation, Eddington has shown, is accurate to a high order of approximation.

To integrate these differential equations, it is now necessary to make certain assumptions, or in other words to adopt a definite stellar model. Eddington assumes that the star consists of a perfect gas of constant molecular weight in which the product ʼn k is invariable throughout the interior. Here is the ratio of the average liberation of energy per gram within any sphere of radius r to the average liberation of energy per gram in the whole star, and k is the mass-coefficient of absorption. On this model and without difficult quadratures it is possible to arrive at two important results-firstly, that the ratio of radiation pressure to gas pressure throughout the star is constant and a function of the stellar mass; and. secondly, that for stars of the same mass the luminos ity varies inversely as ʼn k. A detailed solution by quadratures, integrating from within outwards, as carried through first by Emden, gives the internal distribution of density, pressure and temperature, but involves as an unknown constant the mean molecular weight. The mean molecular weight of course depends upon the degree of ionization in the interior, which in tura depends upon the temperature and pres sure. A solution by trial and error indicates a molecular weight of 2.1 which is adopted for subsequent work. Accordingly when the model star is of the same mass and radius as our sun, its central density turns out to be 76 gms. per cu. cm. and its central temperature forty million degrees. Finally, Kramers' law of absorption is introduced, and this, by virtu of the constant proportionality throughout the mode of the density to the cube of the temperature, reduces to the form that the absorption coefficient varies inversely as the square root of the temperature. Introducing this result into the relation italicized above. the mass luminosity relation is reached

7

log (Luminosity) = log (Mass) radiation pressure 4 +log total pressure

3

+log (Surface temperature + Constant. absorption law), and this is fixed from the mass luminosity and effective temperature of a single star (Capella). It is then found that all thirty-sever stars of known mass and luminosity, both giants and dwarfs, lie on Eddington's mass-luminosity curv

Of the several quantitative predictions furnish by Eddington's model, none is more striking or mor general than this relation that the luminosity of star, apart from a small factor depending upon th surface temperature, is a single-valued function ** its mass. The relation contains but one disposa constant (the proportionality constant of Kramers