fowl, conducted for several years at the Rhode Island Agricultural Experiment Station, there has been evolved a new method for the detection of those birds in a flock that are characterized by higher producing ability. The method is not based upon data involving observed numerical production in any way, but upon the tendency on the part of normal hens to manifest, at certain periods of the year, a gradual increase or a gradual decline in the size and weight of the eggs which they lay.

It has been found that when the numerical production curve of a flock of hens of the same approximate age and condition, and characterized by mediocre producing ability, is plotted on monthly ordinates (aside from the mode of December production of the pullet year which is sometimes manifested if the hens were hatched very early in the season or are high producers) two modes appear, one in April and one in September. These modes, or maxima, represent the peaks of production for the first laying year.

It has also been found that when the curve of mean egg-weight is plotted on similar monthly ordinates, two modal points appear, one in April and the other in September. These weight modes, or weight maxima, are approximately coincident with the production maxima.

When, however, one analyzes the performance of individual birds at the period of these maxima, one finds that, while the majority show an egg-weight which has markedly increased over the mean weight of the first ten eggs laid at the beginning of the laying year, some have not shown such an increase, and some have shown an actual decrease. When the increase or decrease in mean egg-weight is measured as a percentage-increase or as a percentage-decrease, some birds may show an increase of 10 per cent. or more while others show a decrease of equal amount.

The question naturally arose whether the hens which showed the greater increase in mean egg-weight for April or for September also manifested the higher productions for the first laying year. Such correlations were

computed and it was learned that in the majority of cases the hens which gave the higher-percentage increase in egg-weight during these months also showed the higher productions for the year. The flock could easily be separated into production-groups based upon the percentage of increase (or decrease) in mean egg weight. As a rule the correlation was more perfect in September than in April.

Correlations between the percentage of increase in mean egg-weight and numerical production were also attempted when the former were based upon the mean weight of only ten eggs laid as nearly as possible to the absolute weight-mode for April and for September respectively. It was learned from these computations that the correlation was even more perfect when the smaller number of eggs was employed in the computations. The following table gives the results for the autumnal weight maximum, based on the "10-egg test."

From the data presented in the table it appears that higher production is correlated very definitely with higher percentages of increase in egg-weight. The maximum group-production (147) occurred in those hens whose mean increase in egg-weight was above 13 per cent. in the "10-egg test." Selecting above 10 per cent. gave seven birds whose mean production was 143 eggs. Selecting above 6 per cent. gave 12 hens whose mean production was 139 eggs. On the other hand selecting the hens which gave a decrease in egg-weight (" <0 per cent.," in the table), gave five hens with a mean production of only 108.

The superiority of the "10-egg test" in establishing the correlation with numerical production in this instance clearly brings the testing of egg-production of hens into the same class with testing milk-production of dairy cows, in which case Gavin and also Wilson have pointed out that under suitable conditions the one day test may be of greater value than the seven-day, the 30-day or the year test.

With these points openly in mind, and only with the purpose of stimulating further investigation and discussion, the author presents the following brief summary of his results with a single flock as expressing a biological fact which, if later proved to be of general application, may take its place as a fundamental law of production in the domestic fowl:

The innate egg-producing ability of a hen is manifested, not only by the number of eggs laid within a year, or within some longer or shorter period of time, but also by the degree of increase or of decrease in the mean weight of her eggs, when this increase or decrease (calculated as a percentage-increase or percentage-decrease) is measured at those periods of laying (the vernal and autumnal maxima) characterized by the markedly increased laying of the flock; and on this basis, groups of hens characterized by higher producing ability can be differentiated as accurately as, and more easily than by other known means.

The validity of this proposed law of pro

duction is supported by detailed evidence in an article to appear in The American Naturalist. PHILIP HADLEY

R. I. AGRICULTURAL EXPERIMENT STATION

SOCIETIES AND ACADEMIES

THE NATIONAL ACADEMY OF SCIENCES

THE program of scientific sessions of the meeting held in Washington on April 28, 29 and 30, was as follows:

MONDAY, APRIL 28 Morning Session

ALFRED G. MAYOR: The age of the fringing reef of Tutuila, American Samoa.

CHARLES D. WALCOTT: Seaweeds and sponges of the Middle Cambrian.

ROBERT G. AITKEN: The spectra of the visual binary stars.

GEORGE E. HALE, F. ELLERMAN, S. B. NICHOLSON and A. H. Joy: The magnetic polarity of sun spots.

WALTER S. ADAMS and A. H. Joy: The motions in space of some stars of high radial velocity. WALTER S. ADAMS and G. STRÖMBERG: The use of spectroscopic method for determining the parallaxes of the brighter stars.

ADRIAAN VAN MAANEN (introduced by George E. Hale): Evidence of stream-motion afforded by the faint stars in the Orion nebula. GRAHAM LUSK and H. V. ATKINSON: The production of fat from protein after giving meat in large quantity to a dog.

WILLIAM S. HALSTED: End-to-end anastomosis of the intestine-experimental study.

ROBERT M. YERKES (introduced by George E. Hale): Psychological examining in the United States Army.

Afternoon Session FREDERICK H. SEARES (introduced by George E. Hale): Relation between color and luminosity for stars of the same spectral type. FREDERICK H. SEARES, A. VAN MAANEN and F. ELLERMAN (introduced by George E. Hale): Deviations of the sun's general magnetic field from that of a uniformly magnetized sphere. W. W. CAMPBELL: The solar corona. HERBERT E. GREGORY (introduced by W. M. Davis): Plans for exploration of the Pacific. FRANCIS G. BENEDICT, W. R. MILES and ALICE

JOHNSON: The temperature of the human skin.

S. J. MELTZER and M. WOLLSTEIN: The influence of degeneration of a vagus nerve upon the development of pneumonia.

Demonstration of war research problems at the National Bureau of Standards.

Evening Session

William Ellery Hale Lecture, by James Henry Breasted, professor of Egyptology and Oriental history, University of Chicago. Subject: The origin of civilization-from the old stone age to the dawn of civilization.

Reception to members and guests at the United States National Museum, National Gallery of Art.

TUESDAY, APRIL 29 Morning Session

EDWIN H. HALL: The effect of great pressure on the electric conductivity and thermo-electric properties of metals.

EDWIN H. HALL: Comments on the results of Bridgman's experiments.

CHARLES LANE POOR (introduced by J. S. Ames): Line of position computer.

IRVING LANGMUIR: The arrangement of electrons in atoms and molecules.

HENRY F. OSBORN: Paleomastodon, the ancestor of the long-jawed mastodons only.

HENRY F. OSBORN: Seventeenth skeletons of Moropus: probable habits of this animal. THOMAS B. OSBORNE and ALFRED J. WAKEMAN: The preparation of vitamine-free proteins. ARTHUR G. WEBSTER: Tentative results in interior ballistics.

ARTHUR G. WEBSTER: Tentative results in elastic hysteresis.

Afternoon Session

EDWIN H. HALL: Thermal conduction in metals, from the standpoint of dual electric conduction. EDWIN H. HALL: The thermo-electric equation PT dV/dT once more.

A. O. LEUSCHNER and SOPHIA H. LEVY: Perturbations of minor planets discovered by James C. Watson: (104) Clymene (106), Dione (168), Sibylla (175), Andromache. Read by title. ARTHUR G. WEBSTER: The most perfect tuning fork.

ARTHUR G. WEBSTER: Angle of repose of wet sand. EDWARD KASNER: Geometry of the wave equation. C. G. ABBOT: Rotating projectiles from smoothbore guns (illustrated).

C. G. ABBOT: Means for measuring the speed of projectiles in flight (illustrated).

C. G. ABBOT: Recent simultaneous measurements of the solar constant of radiation at Mount Wilson, California, and Calama, Chile (illustrated). JOHN C. MERRIAM: Human remains from the Pleistocene of Rancho La Brea (illustrated). William Ellery Hale Lecture, by James Henry Breasted, professor of Egyptology and Oriental history, University of Chicago. Subject: The origin of civilization—the earliest civilization and its transition to Europe.

WEDNESDAY, APRIL 30

Afternoon Session

Joint session National Academy of Sciences with National Research Council.

GEORGE E. HALE: The past work and future plans of the National Research Council.

JOHN C. MERRIAM: The Division of General Relations, Section on Relations with Educational Institutions and State Committees.

R. A. MILLIKAN: The Division of Physics, Mathematics, Astronomy and Geophysics.

DAYTON C. MILLER: Pressures and velocities, internal and external, due to the discharge of large guns.

E. W. WASHBURN: The Division of Chemistry and Chemical Technology.

A. A. NOYES: Nitrate investigations.

WHITMAN CROSS: The Division of Geology and Geography.

R. G. HUSSEY: The Division of Medicine and Related Sciences.

R. M. YERKES: Psychology in relation to the war. C. E. MCCLUNG: The Division of Agriculture, Botany, Forestry, Zoology and Fisheries.

G. H. CLEVENGER: The Division of Engineering.

The annua! announcement, application blanks, and circular describing graduate courses may be obtained by addressing the Dean of the Johns Hopkins Medical School Washington and Monument St.

Washington University

School of Medicine

REQUIREMENTS FOR ADMISSION Candidates for entrance are required to have completed at least two full years of college work which must include English, German, and instruction with laboratory work in Physics, Chemistry and Biology.

INSTRUCTION

Instruction begins on the last Thursday in September and ends on the second Thursday in June. Clinical instruction is given in the Barnes Hospital and the St. Louis Children's Hospital, affiliated with the medical school, the St. Louis City Hos pital, and in the Washington University DispenERLY.

COURSES LEADING TO ACADEMIC
DEGREES

Students who have taken their premedical work in Washington University, are eligible for the degree of B.S. upon the completion of the first two years of medical work.

Students in Washington University, may pursue study in the fundamental medical sciences leading to the degree of A.M. and Ph.D.

THE LONG ISLAND COLLEGE HOSPITAL

BROOKLYN-NEW YORK

Sixty-first Annual Session begins September 22, 1919

The medical college requires two years of study in a college of liberal arts or sciences for admission.

See specifications for Class A Medical Colleges by the Council on Medical Education, A.M.A.; also those for a Medical Student's Qualifying Certificate by the University of the State of New York.

Conditioned Students not admitted

For particulars address

THE DEAN OF THE COLLEGE OF MEDICINE

Henry and Amity Streets

Clinical instruction is given in the University Hospital on the campus with 400 beds and the immediately adjoining Philadelphia General Hospital with 1600 beds. The fundamental branches are taught in the Hare Laboratory of Chemistry, the combined Laboratories of Pathology, Physiology and Pharmacology, and the Laboratory of Hygiene and Bacteriology.

GRADUATE COURSES

Information concerning courses in the recently organized Medico-Chirurgical College Graduate School of Medicine of the University of Pennsylvania, which includes as a unit the former Philadelphia Polyclinic Hospital and Polyclinic Graduate School of Medicine, can be obtained from the Dean as well as information about courses leading to the degree of Doctor of Public Hygiene (Dr. P.H.) and courses in Tropical Medicine.

The course of instruction occupies four years, begin. ning the second week in September and ending the first week in June. The first two years are devoted to the fundamental sciences, and the third and fourth to practical clinic instruction in medicine and surgery. All the organized medical and surgical charities of the city of Augusta and Richmond County, including the hospitals, are under the entire control of the Board of Trustees of the University. This agreement affords a large number and variety of patients which are used in the clinical teaching. Especial emphasis is laid upon practical work both in the laboratory and clinical departments

TUITION

The charge for tuition is $150.00 a year except for residents of the State of Georgia, to whom tuition it free. For further information and catalogue address

The Medical Department, University of Georgia

AUGUSTA, GEORGIA