A tranistorized d.c. coupled amplifier having very good gain stability, as well as very low drift of the output d.c. level, has been designed. Low frequency input signals with an amplitude of .04 to 2 volts peak-to-peak, approximately, coming from a low impedance source (voice soil of a speaker system) are amplified to an approximate peak-to-peak amplitude of 4 volts. The output is intended to drive a load of the order of 100 kohm.

The analyzer can be operated either internally or externally. The 10 ma germanium discriminator is quiescently biased to 8.5 ma in its low-voltage state. An input signal current of 3.5 ma or more triggers it to its high voltage state. This triggers the oscillator. The oscillator signal is buffered and mixed in the bridge modulator with the reference radiofrequency signal from the cyclotron. The low-frequency beat note from the bridge modulator is squared up and passed to the beat zero univibrator which generates 0.7 mu sec signals each time the beat note passes through zero from positive to negative. The trailing edge of the beat zero univibrator is employed to terminate the time-of-flight measurement and to control the servo measurement. Drawings are included. (M.C.G.)

The object of this report is to acquaint the operator with the operational and technical aspects of the beam current integrator as well as the theory of the system operation. The design and operation of a beam current integrator are described, and the theory of operation is discussed. The instrument has two channels. The console channel is designed to measure the accumulation of charge received by a target during a period of a day no matter what the range used in the experimenter's channel. An analysis indicated that this unit will measure the accumulation of charge by a target to an accuracy of 0.1215% assuming that the constant error due to shorting the integrating capacitor is accounted for. The instrument is ranged to handle from 0.5 to 500 mu a of beam current. (M.C.G.)

A digital-to-analog converter is described which is a part of a system that converts punched-tape digital data to analog data in a series of points drawn by an x-y plotter. The converter is designed to plot accurately tapes that contain information other than coded numerical coordinates. Operation of the converter is also described along with format requirements and power supplies. (J.R.D.)

The power supplies designed and constructed to power high intensity flash tubes used in bubble chamber experiments are briefly described and are accompanied by a schematic diagram of the layout. (D.C.W.)

In order to perform the various experiments with a bubble chamber, a high intensity flash tube is used. This report briefly describes the power supplies designed and constructed to power these lamps.

The potassium-argon age of the Sikhote Alin iron meteorite has been determined. The value is 1.7 + 0.2 x 10⁹ years. Previous lead data suggest an age of 4.6 x 10⁹ years . The date of solidification may be the sum of these two ages.

The propagation of clonal varieties of some orchids is at times exasperatingly slow and occasionally an almost futile effort. Clonal multiplication is generally confined to dividing mature plants and to starting plants from pseudobulbs. There is, of course, the specialized technique for obtaining Phalaenopsis plantlets from the aseptic culture of inflorescence nodes, but this is basically the same thing as propagating plants from pseudobulbs. In certain cases it is highly desirable to rapidly multiply certain clones of orchids. Awarded varieties could thereby be dispersed with great rapidity where now it may take decades for some clones to became fairly common. Commercial flower production would be very much enhanced if certain desirable clones could be multiplied ad infinitum within a short time. Orchid flower production could then be placed more on a par with many of the other cut flowers and the clonal peculiarities of some of the current hybrids could be pampered instead of ignored. This paper describes a tissue culture method for the rapid propagation of Cymbidium clones

Ionizing radiation is useful to plant breeders in obtaining mutations beneficial from an economic point of view. This report, however, concerns our basic knowledge of radiation: attention is here directed to some effects of low level radiation on the R₁ progeny. Approximately one third of the land area of the United States is covered by forest; thus, forest trees form an important component of our natural wealth. It is therefore our obligation to know how these forests will react to low level ionizing radiation. Although this type of radiation might accompany atomic explosions, its effects may not be evident for a number of years.

The sexual reproductive ability of a forest exposed to low level ionizing radiation is dependent on the sensitivity of primordial differentiation, meiotic processes leading to the formation of gametes, fusion of the gametes, and subsequent growth of the sporophytic generations. In this report it was shown that the initiation of reproductive primordia in Pinus rigida, Quercus ilicifolia, Quercus alba and Quercus coccinea is not unusually sensitive to irradiation. Trees which had been severely damaged by chronic low level ionizing radiation (4 to 12 r/20 hr day) were able to differentiate floral structures and produce viable seed. However, flower phenology was retarded, and pronounced morphological aberrations were present. It is suggested that this delay may be the result of a reduction of endogenous growth substances.

In this paper some studies on enzyme properties which are believed to be pertinent to antibodies will be discussed. The particular studies chosen are; (a) the evidence that residues far removed from each other in the sequence play vital roles at the active site; (b) indications on the size of the active site; and (c) evidence for flexibility at the active site. Since the relation between enzyme and antibody is of primary interest an attempt will be made to emphasize the fundamental conclusions derived from the observations and to evaluate critically the deductions on structure and function which derive from these conclusions.