Abstract
A type of radiotherm developed in the Research Laboratories of the General Electric Company was used for the production of the high frequency fields. The oscillator delivered approximately 0.1 ampere per square inch of plate surface at a frequency of 27.3 million cycles (wavelength 11 meters). Cataphoretic measurements were made at level 0.211 D, where D is the total depth of the flat cataphoretic cell in the Mudd assembly of the Northrup-Kunitz apparatus. Measurements during a long series of experiments indicated a mean potential gradient (v/1) of 7.0 ± 0.4 volts per cm. for the field strength, or driving force, in the center of the cataphoretic cell. The mobility, u, is calculated from the relationship:
in which tc is the “cataphoretic time,” that is, the time required by the streptococcus to move over a distance “d” under the influence of the electric field of the cell. Throughout these experiments the room temperature was 25°C., with a variation of ±2°C.
The results of measurements of cataphoretic velocity are presented as distribution curves of cataphoretic time. As the cataphoretic time increases there is, therefore, a reduction in cataphoretic mobility and, presumably, in the net charge on the surface of the streptococcus. The distribution curves are based on the measurements of the velocities of 20 organisms of each suspension. In the distribution curves which are given in this paper, the total amount of energy of the high frequency field to which each of the cultures was exposed is proportional to the time stated in minutes above each distribution curve. The number of each suspension, indicating the order in which cataphoretic measurements were made on a series of tubes, is given in a circle to the left of each distribution curve.
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