162 NATURE AND LIFE. 
sulting phenomena deserve the liveliest interest from a 
theoretical point of view, as well as from their applied 
uses. 
Dutrochet proved, by remarkable experiments, that, 
when a tube closed below by a membrane, and containing 
gum-water, is placed in a vessel containing pure water, the 
level of the gum-water rises little by little through the grad- 
ual introduction of pure water into the tube, while a certain 
quantity of the gum-water inside mingles with the pure 
water outside. In a word, a mutual exchange takes place 
between these two fluids, communicating by the membrane, 
and the current, passing from the thinner liquid toward the 
denser one, is ascertained to be more rapid than that 
moving in the opposite direction. 
This experiment reveals one of the most important phe- 
nomena of life in plants and animals, noted by the word 
endosmosis. Now, Dutrochet had before observed that if 
the positive pole of a battery be inserted in the pure water, 
and the negative pole in the gum-water, the acts of endos- 
mosis are effected more energetically. Onimus and Legros 
discovered, further, that, if the contrary arrangement be 
adopted, that is, if the positive pole be placed in the gum- 
water, and the negative pole in the pure, the level of the 
liquid in the tube descends noticeably, instead of rising. 
Electricity, therefore, can reverse the usual laws of endos- 
mosis. It exerts an influence not less distinct on all the 
other physico-chemical movements, taking place deep in 
the organs. In them it decomposes the salts, coagulates 
the albuminoid elements of the blood and the tissues, just 
as it does in the vessels of the laboratory. Take a very 
curious instance: In chemistry, on decomposing the iodide 
of potassium, iodine is freed, and betrays itself by the 
tinge of intense blue which it develops on contact with 
starch. Now, if an animal be injected with a solution of 
iodide of potassium, and then electrified, it is noticed, after 

