THE PREPARATION OF SECTIONS OF GUINEA PIG LIVER FOR ELECTRON MICROSCOPY.

1. A method is described whereby sections of guinea pig liver cells can be prepared for electron microscopy after fixation. 2.

FACTORS AFFECTING THE GROWTH OF TUBERCLE BACILLI IN LIQUID MEDIA.

1. Certain water-soluble esters of long chain fatty acids (in particular of oleic acid) favor submerged and diffuse growth of mycobacteria throughout the depth of synthetic liquid media. 2.

THE ACTIVATION OF SKIN GRAFTS.

Rabbit skin rendered hyperplastic by various agents showed less tendency than normal skin to contract when sliced off, and when used for grafts it united with the bed more rapidly and was vascularized sooner. The stimulated epidermis proliferated practically at once, and abundantly, to cover adjacent raw surfaces. Also the donor area healed much more swiftly than usual and became infected less often.

PRECIPITIN REACTIONS OF HIGHLY PURIFIED INFLUENZA VIRUSES AND RELATED MATERIALS.

Antisera to purified PR8 virus, to purified protein from normal allantoic fluid, and to purified normal mouse lung particles were obtained from hyper-immunized rabbits and used in quantitative precipitin tests employing various purified preparations of influenza virus and related materials as antigens. The results of those tests indicated that the most highly purified preparations of PR8 or of Lee influenza virus obtained from infectious allantoic fluid contain an antigen characteristic of normal allantoic fluid and likewise that highly purified mouse lung PR8 virus contains an antigen characteristic of normal mouse lungs. Since the infectivity of virus preparations which were ultracentrifugally and electrochemically homogeneous was precipitated by the appropriate antisera to normal antigens, it was concluded that the normal antigens constitute a part of the 100 mmicro particles with which influenza virus activity is at present deemed to be associated.

SUPPRESSION OF GROWTH OF BROWN-PEARCE TUMOR CELLS BY A SPECIFIC ANTIBODY : WITH A CONSIDERATION OF THE NATURE OF THE REACTING CELL CONSTITUENT.

Experiments are reported in detail which show that an antibody which appears in the blood of certain rabbits implanted with the Brown-Pearce tumor or injected with cell-free extracts of it is capable of suppressing the growth of the tumor cells under a variety of experimental conditions, the effects of the antibody being wholly distinct from those of unknown factors that frequently bring about regression of the growth. The implications of the findings are discussed with particular reference to facts indicating that the distinctive cell constituent with which the antibody reacts may play a significant part in the proliferative activities of the Brown-Pearce tumor cell.

STUDIES ON THE CHEMICAL NATURE OF THE SUBSTANCE INDUCING TRANSFORMATION OF PNEUMOCOCCAL TYPES : III. AN IMPROVED METHOD FOR THE ISOLATION OF THE TRANSFORMING SUBSTANCE AND ITS APPLICATION TO PNEUMOCOCCUS TYPES II, III, AND VI.

1. An improved method is outlined for the isolation and purification of the pneumococcal transforming substance. This method makes use of the fact that citrate inhibits the destructive action of the enzyme, desoxyribonuclease, which is released together with the active material during lysis of the living bacterial cells.

STUDIES ON THE CHEMICAL NATURE OF THE SUBSTANCE INDUCING TRANSFORMATION OF PNEUMOCOCCAL TYPES : II. EFFECT OF DESOXYRIBONUCLEASE ON THE BIOLOGICAL ACTIVITY OF THE TRANSFORMING SUBSTANCE.

It has been shown that extremely minute amounts of purified preparations of desoxyribonuclease are capable of bringing about the complete and irreversible inactivation of the transforming substance of Pneumococcus Type III. The significance of the effect of the enzyme, and its bearing on the chemical nature of the transforming substance, together with certain considerations concerning the biological specificity of desoxyribonucleic acids in general, are discussed.

STUDIES ON PNEUMONIA VIRUS OF MICE (PVM) : III. HEMAGGLUTINATION BY THE VIRUS; THE OCCURRENCE OF COMBINATION BETWEEN THE VIRUS AND A TISSUE SUBSTANCE.

1. The cause for the phenomenon of hemagglutination with heated PVM suspensions has been sought. 2.

SOME PROPERTIES OF PROTOPLASMIC GELS : I. TENSION IN THE CHLOROPLAST OF SPIROGYRA.

The chloroplast of Spirogyra is a long, spirally coiled ribbon which may contract to form a short, nearly straight rod. This happens under natural conditions and it can also be produced by a variety of inorganic salts and by some organic substances. It also occurs when the chloroplast is freed by centrifugal force from the clear peripheral protoplasm which is in contact with the cellulose wall.

PURIFICATION AND PROPERTIES OF DESOXYRIBONUCLEASE ISOLATED FROM BEEF PANCREAS.

1. A method is described for the isolation and purification of desoxyribonuclease from a 0.25 N sulfuric acid extract of beef pancreas.

STUDIES ON PNEUMONIA VIRUS OF MICE (PVM) : II. IMMUNOLOGICAL EVIDENCE OF LATENT INFECTION WITH THE VIRUS IN NUMEROUS MAMMALIAN SPECIES.

The results of neutralization tests with PVM and serum obtained from numerous animal species indicate that antibodies agaiust this virus were present in the blood of all mammalian species tested, as not in that of fowls, and that their incidence in various species was widely different. They indicate, also, that in certain species, particularly the cotton rat, there were marked seasonal variations in the incidence of such antibodies; in the late winter and spring the incidence was much higher than during the summer and fall seasons. Cotton rats and hamsters which did not possess neutralizing antibodies against PVM were susceptible to manifest pulmonary infection with this virus, irrespective of the effects of previous experiments upon them, whereas those which possessed such antibodies were immune.

STUDIES ON PNEUMONIA VIRUS OF MICE (PVM) : I. THE PRECISION OF MEASUREMENTS IN VIVO OF THE VIRUS AND ANTIBODIES AGAINST IT.

This study on pneumonia virus of mice (PVM) was carried out in order to obtain as accurate data as possible on the degree of variation which may be expected in titrations of the virus or of antibodies against it in vivo. It is believed that the knowledge gained will facilitate further investigations on this latent pneumotropic virus and make possible a more exact assessment of the significance of experimental results obtained with the agent. The reproducibility of 50 per cent maximum score titration end points with PVM in mice is such that the chances are 19 out of 20 that a difference of 1.

THE PREPARATION OF HIGHLY PURIFIED PR8 INFLUENZA VIRUS FROM INFECTED MOUSE LUNGS.

Highly purified preparations of PR8 influenza virus were obtained from perfused, infected mouse lungs by a combination of methods involving adsorption of the virus on and elution from chicken red cells and differential centrifugation. Such preparations were found to possess 50 per cent infectivity end-points at 10(-11) to 10(-11.8), and 10(-13) to 10(-14.

ENDURING IMMUNITY FOLLOWING VACCINATION OF MICE WITH FORMALIN-INACTIVATED VIRUS OF RUSSIAN SPRING-SUMMER (FAR EASTERN, TICK-BORNE) ENCEPHALITIS : CORRELATION WITH SERUM-NEUTRALIZING AND COMPLEMENT-FIXING ANTIBODIES.

A single course of two intraperitoneal injections of formalin-inactivated virus of Russian spring-summer encephalitis induced in albino mice a solidly immune state which endured almost throughout life. Active virus is therefore not essential for the production of a high degree of lasting immunity. The immune response to vaccination consists of resistance to peripherally introduced active virus and development of circulating antibody.

STUDIES ON THE BIOCHEMICAL, BIOPHYSICAL, AND IMMUNOGENIC PROPERTIES OF JAPANESE B TYPE ENCEPHALITIS VIRUS AND VACCINES.

Studies on the biochemical, biophysical, and immunogenic properties of Japanese B type encephalitis virus and vaccines have been made in order to determine whether a purified vaccine suitable for human use could be obtained by means of differential centrifugation of extracts of infected mouse brains. Studies were also made on extracts of normal mouse brains, it was found that extracts of normal as well as of infected mouse brains contained fairly large amounts of several components of high molecular weight. Components having sedimentation constants near 5 and 40 Svedberg units were found in extracts of infected brains.

WATER RELATIONS IN THE CELL : I. THE CHLOROPLASTS OF NITELLA AND OF SPIROGYRA.

Chloroplasts may contract under natural conditions and give up water to the rest of the cell, thus indicating changes in metabolism or constitution. Such contractions may be produced experimentally. In Nitella the chloroplasts are ellipsoid bodies which, under natural conditions, may contract to spheres with a loss of volume.

HEREDITARY ACHONDROPLASIA IN THE RABBIT : II. PATHOLOGIC ASPECTS.

Pathological observations on hereditary achondroplasia in the rabbit have been described. At autopsy, the chief features of interest are: reduced size with disproportionately shortened extremities and large head, cutaneous and subcutaneous edema of variable degree and distribution, small shortened bones with a cartilaginous appearance and texture, immature teeth, and cleft palate in one-fourth the cases; blood-stained fluid in the thoracic and abdominal cavities; a comparatively small heart pointing to the right of the midline, a very large firm thymus, a large pale soft spleen, a large swollen liver with red mottling, and a stomach distended with thin greenish mucus but no milk. The mean relative weights of all organs in terms of the net body weight were larger than those of normal new-born litter mates.

HEREDITARY ACHONDROPLASIA IN THE RABBIT : I. PHYSICAL APPEARANCE AND GENERAL FEATURES.

An achondroplastic condition in the rabbit has been described. It is present at birth and is characterized by size reduction, by a disproportion of bodily parts, most marked in the extremities, and by an invariably lethal effect. The animals are still-born or die very shortly after birth.

EFFECTS OF HYDROXYL ON NEGATIVE AND POSITIVE CELLS OF NITELLA.

Remarkable changes are brought about by KOH in transforming negative cells of Nitella (showing dilute solution negative with KOH) to positive cells (showing dilute solution positive with KOH). NaOH is less effective as a transforming agent. This might be explained on the ground that the protoplasm contains an acid (possibly a fatty acid) which makes the cell negative and which is dissolved out more rapidly by KOH than by NaOH, as happens with the fatty acids in ordinary soaps.