THE RATE OF OVULATION IN THE DOMESTIC FOWL DURING THE PULLET YEAR

The rate of ovulation of the domestic fowl may be expressed by the equation of an autocatalytic chemical reaction. This is not surprising in view of the fact that the rate of growth may also be expressed by such an equation, and that the rate of ovulation is probably an index of the growth of the eggs. This brings the phenomenon of ovulation in the hen under the general subject of growth, and substantiates the generality and the probability of the hypothesis that growth, or at any rate the limiting factor of growth, is an autocatalytic reaction.     

THE TURNOVER RATE OF PHOSPHOLIPIDS IN THE PLASMA OF THE DOG AS MEASURED WITH RADIOACTIVE PHOSPHORUS

1. A method for the determination of turnover time and turnover rate of plasma phospholipid is presented. 2. During the postabsorptive state 5.2 to 8.0 mg. of phospholipid phosphorus are turned over per hour in the plasma of dogs weighing 6–9 kilos. 3. The amount of phospholipid in an organ that is supplied by plasma phospholipid per hour is calculated.     

RATE OF RESPIRATION AS RELATED TO AGE

In the present paper it is shown that as the leaves of corn, sorghum, wheat, and oats increase in age there is a decrease in rate of respiration; but that as the leaves become still older (past about middle age) the rate gradually increases.     

THE INHIBITION OF CAROTENOID ACCUMULATION IN NAVEL ORANGES BY GIBBERELLIN A3 AS MEASURED BY THIN LAYER CHROMATOGRAPHY

A study of the changes in carotenoid level in the Navel orangerind following color break supported existing evidence thatlight increases the level of carotenoids and that the periodof carotenoid accumulation ceases at a certain time, regardlessof the level of color attained. It was also shown that GA retards the accumulation of rind carotenoidsand that this effect is on general carotenoid synthesis ratherthan alteration of the ratios of individual carotenoids. A method for thin layer chromatography of carotenoids was described,using silica gel as a base. ¹ Paper No. 1562.     

OSMOTIC RELATIONSHIPS IN THE HEN'S EGG AS DETERMINED BY RELATIVE VAPOR PRESSURES

It has been shown by a comparison of the relative vapor pressures of egg yolk and egg white before and after the addition of sodium chloride to the white that the osmotic pressure of the yolk is greater than that of the white.     

DURATION OF THE NUCLEAR CYC LE IN TRADESCANTIA PALUDOSA ROOT TIPS AS MEASURED WITH H3-THYMIDINE

Wimber , Donald E. (Brookhaven National Lab., Upton, N. Y.) Duration of the nuclear cycle in Tradescantia paludosa root tips as measured with H³-thymidine. Amer. Jour. Bot. 47(10): 828–834. Illus. 1960.—The duration of the nuclear cycle and its various subdivisions were measured in Tradescantia root tips by autoradiographic techniques. H³-thymidine was used as a nuclear label and was supplied to the roots for 0.5 hr. After labeling, the roots were allowed to grow in the absence of label for periods up to 38 hr. By determining the percentage of divisions labeled at the various times of fixation, a reconstruction of the nuclear cycle could be made. The average cycle was determined as 20 hr. in duration, DNA synthesis 10.8 hr., presynthetic interphase 4 hr., postsynthetic interphase 2.7 hr., prophase 1.6 hr., metaphase 0.3 hr. and anaphase-telophase 0.6 hr. Approximate standard deviations for the duration of some of the subdivisions were calculated.