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microscope as light spots without the iodine municipal abattoir of that city to procure a treatment, and an enormous number of the large series of ovaries of the cow. He was cells are scattered over the yolk sac. The able to obtain records of the last appearance cells of the small-mouthed black bass are of eestrus in a certain number of animals large and contain much glycogen which dis- (apparently 33) and has given a set of handsolves very readily in water after iodine stain- some plates illustrating the rise and retroing. I have noted in pike-perch which have gression of the corpus luteum. From the been kept under observation for a consider

gross appearances and from measurements (no able time that their glycogen cells become microscopic studies were made) Küpfer states greatly diminished in number. I have not that the intercestral period of 21 days may be been successful in finding the glycogen cells divided into two parts. During the first in all species of fish. I have never been able 10–11 days after ovulation the corpus luteum to discover them in Fundulus, and have sought is slowly reaching its full size, and thereafter for them in vain in recently hatched smelt. it is in a state of retrogression which conThey evidently act as temporary reservoirs of tinues throughout the next interval, until by glycogen, but why they are present in some the time of the second following ovulation (42 species of recently hatched fish, and not in days) the corpus luteum is macroscopically others, is not apparent.

insignificant. The ovaries of animals underIf it should be discovered that these going uninterrupted æstrus cycles will there peculiar cells can be isolated and satisfac- fore contain the follicles and corpora lutea torily cultivated in artificial media, they will of two or three periods, at successive stages offer most promising material for studying of growth and retrogression. experimentally the formation of glycogen. The present writer has been endeavoring to

piece out a similar account of the pig, in FREDERICK W. ELLIS MONSON, Mass.,

order to provide an anatomical basis for the August 23, 1920

physiological relations of ovary, ovum, and

uterus in this species, and has published a THE OVARIAN CYCLE OF SWINE

description of the mature follicles and devel

oping corpora lutea up to the tenth or Most of our information regarding the

eleventh day, but has been unable, until the changes in the mammalian ovary during the

present, on account of conditions of the meatvarious events of the reproductive cycle has

packing trade, to follow the animals longer been gained from study of the laboratory rodents and small carnivores. The domestic

than this time. The lacking material has ungulates, on account of their large size

now been supplied, through the cooperation and commercial value, have been neglected

of Mr. W. N. Cooper, manager of the Amerin this respect, although they promise certain

ican Feeding Company of Baltimore, at whose advantages because of the simplicity of their

large piggery farm a series of 22 sows has ovarian structure and the regular, outspoken

been obtained covering practically every day appearance of estrus.

of the 21-day cycle. The only attempt to follow the history of

The story as read from these specimens is the ripening follicles and the corpora lutea

a simple one, as will be seen from the accomof an ungulate, with material of known his- panying diagram. It appears that mature tory, is that recently published by Max ovaries of non-pregnant animals contain a reKüpfer of Zurich, who made use of the

serve stock of follicles of 5 mm. diameter or 1 Küpfer, Max, “Beiträge zur Morphologie der 2 Corner, G. W., “On the origin of the corpus weiblichen Geschlechtsorgane bei den Säugetieren,"

luteum of the sow from both losa and theca Denksschr. d. Schweiz. Naturf. Gesellsch., 1920, Bd. interna," Amer. Jour. Anat., 1920, Vol. 26, pp. LVI.


less. One or two days before the onset of When the pig's ova are fertilized, the emcestrus some of the follicles rapidly enlarge bryos gain attachment to the uterine wall beto the full diameter of 7 to 10 mm., and the tween the tenth and fifteenth day after enclosed ova pass through the preliminary ovulation. It is a most important fact, therestages of maturation. Ovulation occurs on fore, that the corpus luteum persists until the second of the three days of estrus; the the fourteenth or fifteenth day, for this find

are three days on route through the ing harmonizes with the current hypothesis Fallopian tube and pass into the uterus on that the corpus luteum exercises an effect the fourth day. If not fertilized they degen- upon the uterus, preparing it for implantaerate in utero about the seventh or eighth tion. The duration of the corpus luteum is day after ovulation. The corpora lutea, as quite variable in different species, but in none already described, reach full histological com- has it been found less than the time required plexity about the seventh day, by which time for attachment of the embryos. Another sup


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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 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 intercestral 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.

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.



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.


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 (illus

trated): 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 (illus

trated): 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.

MERRILL (introduced by Whitman Cross). The Island of Tagula (New Guinea), its satellites

and coral reefs; The shallow seas of Australasia:

W. M. DAVIS. 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.

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 (illus

trated): C. G. ABBOT, The evolution of matter: F. W. CLARKE. The differences between variable series: FRANZ

Boas. 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 (illus

trated): 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


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. 8. National Museum.

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 (illus

trated): GRAHAM LUSK. The physical and chemical behavior of proteins

(illustrated): JACQUES LOEB. The skin temperature of Pachyderms (illustrated):


MARION L. BAKER. The temperature factor in phytopathology (illus

trated): L. R. JONES. Results of feeding experiments with mixtures of

food stuffs in unusual proportions (illustrated):

T. B. OSBORNE and L. B. MENDEL. Population (illustrated): C. B. DAVENPORT, Measuring higher grades of intelligence: E. L.

THORNDIKE. A study of specific forces of mortality: RAYMOND



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.






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Admits only college degree students and
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Johns Hopkins University

Medical School The Medical School is an Integral part of the University and is in close Affiliation with the Johns Hopkins Hospital

ADMISSION Candidates for admission must be graduates of approved colleges or scientific schools with at least two year's instruction,

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Affiliated with the New Haven Hospital
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