ELECTROPHYSIOLOGY 333 



powerful electromagnet. But nothing happened; the egg con- 

 tinued its process of division in quite the normal way. Still, 

 hypotheses of the movement and orientation of chromosomes 

 based on magnetic forces continue to be advanced. It has been 

 found that magnets when floating on corks on water assume the 

 same relative positions as do chromosomes. 



Electrostatics. — Under electrostatics we shall consider but 

 one phenomenon, viz., the effect of static electricity on plant life. 

 Experimental work of this nature has been done under the name 

 of electroculture. That the air is electrically charged with respect 

 to the earth, the difference in potential increasing with height, 

 leads to the conclusion that plants out of doors with their roots 

 in the earth and their tops in the air are constantly being traversed 

 by minute currents of electricity. It is reasonable to assume 

 that an increase or decrease in this current should affect the 

 growth of the plant. From able investigators comes evidence 

 interpreted by them as demonstrating that increased plant 

 growth follows electric excitation of a certain intensity and dura- 

 tion, supplied from a charged network suspended above the 

 plants. These investigations were begun by Oliver Lodge. 

 Later, L. J. Briggs and other American workers took up the work 

 and over a period of ten years treated plants in the field and in 

 the greenhouse, under very carefully controlled conditions, with, 

 throughout, negative results. There is a possible interpretation 

 of the difference in results between American and English 

 workers; if electricity is a substitute for light, an additional 

 supply of it would, in England, be of advantage to the plants; 

 but in America, where the average daily sunhght is in excess of 

 the plants' needs, more energy in the form of a substitute would 

 be of no benefit. 



Work by Marinesco indicates that the beneficial effect of a 

 static electric field may be due to an acceleration in the ascent of 

 sap. The ascent of sap in plants is augmented by applying an 

 electric field, provided the positive pole of the field is above the 

 plant (Fig. 164). In order to obtain noticeable results, it is 

 necessary to treat a plant in which the flow of sap is great, 

 such as in tobacco. 



Electric Currents. — Experimental physiology as we know it 

 today began with the observation of Galvani that a muscle 

 contracts if touched by two metal strips, one of copper and one of 



