microscope as light spots without the iodine treatment, and an enormous number of the cells are scattered over the yolk sac. The cells of the small-mouthed black bass are large and contain much glycogen which dissolves very readily in water after iodine staining. I have noted in pike-perch which have been kept under observation for a considerable time that their glycogen cells become greatly diminished in number. I have not been successful in finding the glycogen cells in all species of fish. I have never been able to discover them in Fundulus, and have sought for them in vain in recently hatched smelt. They evidently act as temporary reservoirs of glycogen, but why they are present in some species of recently hatched fish, and not in others, is not apparent. If it should be discovered that these peculiar cells can be isolated and satisfactorily cultivated in artificial media, they will offer most promising material for studying experimentally the formation of glycogen. MONSON, MASS., August 23, 1920 FREDERICK W. ELLIS THE OVARIAN CYCLE OF SWINE MOST of our information regarding the changes in the mammalian ovary during the various events of the reproductive cycle has been gained from study of the laboratory rodents and small carnivores. The domestic ungulates, on account of their large size and commercial value, have been neglected in this respect, although they promise certain advantages because of the simplicity of their ovarian structure and the regular, outspoken appearance of œstrus. The only attempt to follow the history of the ripening follicles and the corpora lutea of an ungulate, with material of known history, is that recently published by Max Küpfer of Zurich, who made use of the 1 1 Küpfer, Max, "Beiträge zur Morphologie der weiblichen Geschlechtsorgane bei den Säugetieren," Denksschr. d. Schweiz, Naturf. Gesellsch., 1920, Bd. LVI. municipal abattoir of that city to procure a large series of ovaries of the cow. He was able to obtain records of the last appearance of œstrus in a certain number of animals (apparently 33) and has given a set of handsome plates illustrating the rise and retrogression of the corpus luteum. From the gross appearances and from measurements (no microscopic studies were made) Küpfer states that the intercestral period of 21 days may be divided into two parts. During the first 10-11 days after ovulation the corpus luteum is slowly reaching its full size, and thereafter it is in a state of retrogression which continues throughout the next interval, until by the time of the second following ovulation (42 days) the corpus luteum is macroscopically insignificant. The ovaries of animals undergoing uninterrupted astrus cycles will there fore contain the follicles and corpora lutea of two or three periods, at successive stages of growth and retrogression. The present writer has been endeavoring to piece out a similar account of the pig, in order to provide an anatomical basis for the physiological relations of ovary, ovum, and uterus in this species, and has published a description of the mature follicles and developing corpora lutea up to the tenth or eleventh day, but has been unable, until the present, on account of conditions of the meatpacking trade, to follow the animals longer than this time. The lacking material has now been supplied, through the cooperation of Mr. W. N. Cooper, manager of the American Feeding Company of Baltimore, at whose large piggery farm a series of 22 sows has been obtained covering practically every day of the 21-day cycle. The story as read from these specimens is a simple one, as will be seen from the accompanying diagram. It appears that mature ovaries of non-pregnant animals contain a reserve stock of follicles of 5 mm. diameter or 2 Corner, G. W., "On the origin of the corpus luteum of the sow from both granulosa and theca interna," Amer. Jour. Anat., 1920, Vol. 26, pp. 117-183. less. One or two days before the onset of œstrus some of the follicles rapidly enlarge to the full diameter of 7 to 10 mm., and the enclosed ova pass through the preliminary stages of maturation. Ovulation occurs on the second of the three days of oestrus; the ova are three days en route through the Fallopian tube and pass into the uterus on the fourth day. If not fertilized they degenerate in utero about the seventh or eighth day after ovulation. The corpora lutea, as already described, reach full histological complexity about the seventh day, by which time oestrus When the pig's ova are fertilized, the embryos gain attachment to the uterine wall between the tenth and fifteenth day after ovulation. It is a most important fact, therefore, that the corpus luteum persists until the fourteenth or fifteenth day, for this finding harmonizes with the current hypothesis that the corpus luteum exercises an effect upon the uterus, preparing it for implantation. The duration of the 'corpus luteum is quite variable in different species, but in none has it been found less than the time required for attachment of the embryos. Another sup oestrus DIAM IN MM. 10. 7 2. 1. they have attained a diameter of 9 mm. The new specimens show that they remain in a state of full development, without obvious further change, until the fourteenth or fifteenth day after discharge of the follicles, and then begin a retrogression which is initiated by a sudden disintegration of the granulosa lutein cells, which have formed the chief bulk of the organ. In a few days more the corpora consist only of connective tissue containing in its meshes a few lipoid-laden cells; and by the time of the next ovulation they have diminished in size to a diameter of 6 mm. During the second interœstral interval after their formation they shrink still further, until at the age of 40 days they are but 2 or 2.5 mm. in diameter. After this they are not readily distinguishable from other ovarian tissues in the gross, and microscopically are so far degenerated that one does not feel able to separate them from atretic follicles. position with regard to the function of the corpus luteum, that it serves, while present, to restrain the growth of follicles, is also borne out by our observations, as far as they go, for it will be noticed that a new group of follicles passes beyond the resting dimension only after the degeneration of the last corpora is under way. A full account of these studies will form part of a monograph on cyclic changes in the ovaries and uterus of the pig, now in preparation. GEORGE W. CORNER JOHNS HOPKINS MEDICAL SCHOOL THE NATIONAL ACADEMY OF SCIENCES THE annual meeting of the National Academy of Sciences was held at the Natural History Building, U. S. National Museum, in Washington on April 25, 26 and 27, 1921. The preliminary program of scientific sessions open to the public follows. MONDAY, APRIL 25 Afternoon Session Ultimate rational units (illustrated): GILBERT N. LEWIS. The quantum law and the Doppler effect: WILLIAM DUANE. Preliminary measurements of the effect of high pressures on the thermal conductivities of liquids (illustrated): P. W. BRIDGMAN. The stratification of suspended particles (illustrated): C. E. MENDENHALL and MAX MASON. Transmission characteristics of the submarine cable (illustrated): J. R. CARSON and J. J. GILBERT (introduced by J. J. Carty and F. B. Jewett). Radiation from transmission lines: J. R. CARSON (introduced by J. J. Carty and F. B. Jewett). Application of the principle of similitude to the hydraulic problem of the surge chamber (illustrated): W. F. DURAND. Theories of osmotic pressure; Comments on the Borelius space-lattice theory of the metallic state: E. H. HALL. Metamorphism in meteorites (illustrated): G. P. On the radiation of energy from coils in wireless telegraphy; On the vibrations of gun-barrels; On the problem of steering an automobile around a corner: A. G. WEBSTER. Evening Session Address by His Serene Highness Albert I., Prince of Monaco, Agassiz medalist, Auditorium U. S. National Museum. Reception to the Prince, Galleries, U. S. National Museum. TUESDAY, APRIL 26 Morning Session A model of the solar gravitational field: EDWARD KASNER. On the problem of three or more bodies: GEORGE D. BIRKHOFF. Quaternions and their generalizations: L. E. DICKSON. Investigations in algebra and number theory: L. E. DICKSON. On the approximate solutions in integers of a set of linear equations: H. F. BLICHFELDT. A provisional theory of new stars: H. N. RUSSELL. The compilation of star catalogues by means of a doublet camera (illustrated): F. SCHLESINGER. The National Research Council: VERNON KELLOGG. The order of the stars (illustrated): W. S. ADAMS. Cooking with solar heat on Mt. Wilson (illustrated): C. G. ABBOT. The evolution of matter: F. W. CLARKE. Life of James Hall, of Albany, geologist and paleontologist, 1811-1890 (by title): J. M. CLARKE, Afternoon Session The classification of animals: AUSTIN H. CLARK. Attempts to acclimatize Aphelinus mali in France, South Africa, New Zealand and Uruguay (illustrated): L. O. HOWARD. Note on structure of the trilobite (illustrated): C. D. WALCOTT. Origin and history of the Ursidae or bears in the Western Hemisphere, with particular reference to the bearing of this question on problems of geographical history (illustrated): J. C. MER RIAM. The evolution, phylogeny and classification of the Proboscidea (illustrated): H. F. OSBORN. Experiments in epidemiology: SIMON FLEXNER. Effect of administering various simple metabolites upon the heat production of the dog (illustrated): GRAHAM LUSK. The physical and chemical behavior of proteins (illustrated): Jacques Loeb, The skin temperature of Pachyderms (illustrated): FRANCIS G. BENEDICT, EDWARD L. Fox and MARION L. BAKER. The temperature factor in phytopathology (illustrated): L. R. JONES. Results of feeding experiments with mixtures of A study of specific forces of mortality: RAYMOND SMITHSONIAN INSTITUTION, WASHINGTON C. G. ABBOT, Home Secretary ADMISSION Candidates for admission must be graduates of approved colleges or scientific schools with at least two year's instruction, including laboratory work, in Chemistry, and one year each in physics and biology, together with evidence of a reading knowledge of French and German. Each class is limited to 90 students, men and women being admitted on the same terms. Except in unusual circumstances, applications for admission will not be considered after July 1st. If vacancies occur, students from other institutions desiring advanced standing may be admitted to the second or third year provided they fulfill all of our requirements and present exceptional qualifications. The charge for tuition is $250 per annum, payable in three instalments. There are no extra fees except for rental of microscope, certain expensive supplies, and laboratory breakage. The annual announcement and application blanks may be obtained by addressing the Dean of the Johns Hopkins Medica School Washington and Monument Sts. BALTIMORE, M.D SUMMER WORK FOR GRADUATES Beginning Tuesday, June 6th, and ending Thursday, July 16th, a course in medical diagnosis, including laboratory exercises in clinical pathology and demonstrations in pathological anatomy, will be offered. The course will be limited to twenty students, fee $100. Applications should be made to the Dean's Office. Louisiana SCHOOL OF MEDICINE (Established in 1834) ADMISSION: All students entering the Freshman Class will be required to present credits for two years of college work, which must include Chemistry (General and Organic), Physics and Biology, with their laboratories, and at least one year in English and one year in a modern foreign language. COMBINED COURSES: Premedical course of two years is offered in the College of Arts and Sciences, which provides for systematic work leading to the B.S. degree at the end of the second year in the medical course. School of Pharmacy, School of Dentistry and Graduate School of Medicine also. Women admitted to all Schools of the College of Medicine For bulletins and all other information, address Tulane College of Medicine P. O. Box 770 New Orleans, La. Marine Biological Laboratory Woods Hole, Mass. INVESTIGATION Entire Year INSTRUCTION June 29 to August 9 1921 SUPPLY DEPARTMENT Open the Entire Year Facilities for research in Zoology, Embryology, Physiology, and Botany. Eighty-four private laboratories, $100 each for not over three months. Thirty tables are available for beginners in research who desire to work under the direction of members of the staff. The fee for such a table is $50.00. Courses of laboratory instruction with lectures are offered in Invertebrate Zoology, Protozoology, Embryology, Physiology and Morphology and Taxonomy of the Algae. Each course requires the full time of the student. Fee, $75. A lecture course on the Philosophical Aspects of Biology and Allied Sciences is also offered. Animals and plants, preserved, living, and in embryonic stages. Preserved material of all types of animals and of Algae, Fungi, Liverworts and Mosses furnished for classwork, or for the museum. Living material furnished in season as ordered. Microscopic slides in Zoology, Botany, Histology, Bacteriology. Price lists of Zoological and Botanical material and Microscopic Slides sent on application. State which is desired. For price lists and all information regarding material, address GEO. M. GRAY, Curator, Woods Hole, Mass. The annual announcement will be sent on application to The Director, Marine Biological Laboratory, Woods Hole, Mass. Stanford University Medical School The Medical School of Leland Stanford Jr. University is an integral part of the University, and its Faculty controls the Lane and the Stanford University Hospitals, which together with the Lane Medical Library, are administered by the Trustees of the University. Admission Instruction Tuition Three years of University instruction, in- The tuition fee is $50 per quarter for twelve For information address THE DEAN of the Stanford University Medical School, 2398 Sacramento Street, San Francisco, California. |