198 Scientific Proceedings (108). 



Healthy animals, for experimental work, are only to be secured 

 by individual selection, as not all members of a litter are equally 

 healthy, but too rapid breeding of healthy animals is sure to pro- 

 duce weak offspring. Extreme heat will kill mice quicker than 

 cold. Pulmonary diseases must be guarded against by rapid 

 removal of infected animals. Sarcomas have also caused the 

 death of a number of animals in the course of this investigation, 

 usually not appearing in animals less than a year old. Tape-worm 

 cysts have been found in the livers of some mice, but seemed to 

 have been without effect on the general health and reproductive 

 activity of their hosts. 



A few female white mice have shown a peculiarity common in 

 yellow mice, sterility accompanied by extensive laying down of 

 fat, after having four to six litters. The cause of this behavior is 

 at present unknown. 



105 (1565) 



Reaction of cells to the galvanic current in tissue cultures. 



By Sven Ingvar (by invitation). 



[From the Osbom Zoological Laboratory, Yale University, New 



Haven, Conn.] 



By applying a weak constant galvanic current (strength 

 2-4 billionths of an ampere, density approximately 1/1000-1/2000 

 5, nonpolarizable electrodes) to tissue cultures made according to 

 Harrison's method, the following observations were made: 



The galvanic current has a directing influence upon the 

 cell and fiber outgrowth in the cultures so that this occurs almost 

 entirely along the lines of force in the galvanic field. Whereas 

 in the control preparations the outgrowth occurs in all directions, 

 cell movements under the influence of a galvanic current take 

 place toward the anode and the cathode. The cell processes 

 growing toward the anode show morphological differences from 

 those growing toward the cathode. A new biological cell character 

 may in this way be revealed. 



If a weak electric current by means of a single conductor is 

 drawn through the culture, the outgrowth of the fibers and cells 



