158 NATURE AND LIFE. 



tions with the fluids that moisten them, we find that they 

 give rise to an infinite number of pairs constantly evolving 

 electricity. The blood of the arteries with that of the 

 veins forms a pair, having an electro-motive power of 0.57, 

 that of a pair with nitric acid being 100. Becquerel ex- 

 plains, by the intervention of these currents, many physio- 

 logical phenomena hitherto imperfectly understood. Grant- 

 ing the reality of such actions, yet it must be acknowledged 

 that the general doctrine which combines them each with 

 the other, and links the whole together with the various 

 modes of action of the organism, is far from being clear 

 and precise. We need to know how these currents are 

 distributed and circulate, what lines and courses they fol- 

 low. It is now time for experimental physiology to at- 

 tack these difficult problems, the solution of which is abso- 

 lutely necessary for accurate knowledge of vital determi- 

 nations, that is, for the computation and the estimate of 

 those various factors which are terms in all the equations 

 of organic movement. 



Vegetables, too, develop electricity. Pouillet has 

 clearly demonstrated that vegetation throws it off. Other 

 physicists, particularly Becquerel, have proved the exist- 

 ence of currents in the fruits, stems, roots, and leaves of 

 plants. Becquerel took a branch of young poplar full of 

 sap, introduced a platinum wire into the wood and another 

 into the bark, and brought the two ends of the conductors 

 together in a galvanoscope the needle at once showed the 

 passage of a current. Buff has lately made experiments, 

 taking care not to injure the organs. Two vessels contain- 

 ing mercury received platinum wires; over the mercury 

 stood water containing the vegetables to be examined as to 

 their electric condition. Taking the leaves and roots, Buff 

 proved a current passing through the plant from the roots 

 to the leaves ; in a branch severed from the stem the cur- 

 rent passed toward the leaves, too. To sum up, the exist- 



