Bioelectric Potentials of Tumor-Infected Plants.

Bioelectric potentials are considered by BURR (2) to be a vital part of life processes, and any change affecting life processes is bound to exert an effect on these potentials. There is little doubt that radiation injury exerts a profound effect on the potentials of the avian embryo, as shown by ROMANOFF and BLESS (7) and on seeds as found by BLESS (1) and JONES et al. (6). The effect of tumor on the potentials is not so unambiguous. BURR and coworkers (3) found changes in the potential, measured across the clhest of mice witlh induced tumors, the chiaracter of the changes being dependent on the age and the strain of the animials. The work of BURROWS et al. (4) seems to contradict these findings. The object of these experiments is to study the effects of tulmior on the potential of plants. Two sets of experiments separated by a considerable time interval lhave been performied with results that are essentially similar. The circuit for measuring potentials was essentially a bridge network using an FP54 electromieter tube (5) in vacuo with an input resistance of 1.16 x 1011 ohlmis. With the voltages of the plants used the current was below 10-12 amiiperes. Contact with the plants was made by means of felt brushes moistened w-ith a KCl solution flowing fromitest tubes into wlhich were immiiersedl Ag-AgCl electrodes. The sensitivity of the apparatus was about 0.1 mv./div. Tomiiato plants were clhosen for this study because of their relative homogeneity. Two groups of 30 plants each were cultivated; one group in sixinch standard flower pots, the other in four-inch pots. Fifteen of the plants in the six-inch together with 10 of the plants in the four-inch pots were maintained as control. All plants were inoculated; those in the experimental groups with a strain of Phytomzonas tumefaciens which produces a hairy tumiior, and those in the control groups witlh distilled water. The latter action was taken so that effects due to external injury would be the same for all plants. The injections were made with a hypodermic needle at a depth of about 1 mmin. below the surface. Precautions were taken to be able to locate the exact spot of the inoculation. The plants were protected with bandages at the point of insertion of the needle to prevent further infection. The plants were approximately 50 cm. in height at the time of inoculation, and about 1 cmii. in diamiieter. The potential of each plant at the point of inoculation relative to a point directly across the stemlwas measured at the same tiim-e of day on alternate days. Resistance measuremiients were at first taken across the samiie portion