ELECTRICITY IN THE PHENOMENA OF ANIMAL LIFE. 439 



identical aggregate of causes, liave we not groimd for supposing, by 

 reason of analogy, that iu every exothermic physical phenomenon the 

 energy set free appears, or tends to ap^Dcar, first under the form of 

 electricity? That if we have not hitherto succeeded iu completely 

 revealing it in this form, it is because the very circumstances of our 

 experiments have occasioned its transformation. 



If this conjecture be vindicated we shall be authorized to regard all 

 the i^henomena of nature, whatever they may be, as manifestations of 

 electricity, without deciding beforehand anything as to the essential 

 nature of this force. 



This is the form under which the idea presents itself to my mind of 

 the unity of the forces of nature. 



II. 



OF THE LIVING MOTOR. 



I. — OF THE NATUKK OK TllK LIVING MOTOR. 



- - - Among the essential characteristics presented by the animal 

 kingdom, one of the most striking is unquestionably the faculty of 

 automatic locomotion, which has been called motivity. 



The study of this distinctive quality leads us quite naturally to the 

 most general consideration of the i)henomena of life in their connected 

 aggregate, so that we may conveniently take this as our starting jx^int 

 when we propose to unfold the part takeu by the forces of inanimate 

 nature iu connection with the phenomena in question. Since motivity 

 is essentially inherent in the nature of the living animal organism, we 

 may say that an animal is a motor; further than this, we have good 

 reason to believe that an animal is an electric motor, as I will now try 

 to show. 



Proceeding by the method of exclusion, we see at the outset that 

 motivity can not arise from a dynamic transformation of potential 

 energy of the kind presented to us in a hydraulic motor, for we per 

 ceive neither a reservoir of liquid nor a fall capable of being turned to 

 account. *" 



Neither can the cause we seek be found in a purely thermic transfor- 

 mation of the same kind as that exhibited by gas engines, hot-air engines, 

 and steam engines, to which contrivances no one would think of com- 

 paring a muscle. 



On the other hand, electricity lends itself to a satisfactory solution 

 of the problem before us, a solution to which it will be well that we give 

 our attention, at any rate until the future shall hav^e revealed to us the 

 existence of some other as yet uuthought-of mode of transformation of 

 energy, if so be that such a mode exist. 



Laying aside, then, finally, on the evidence before us, the supposition 

 of hydraulic action, let us examine more closely the two other hypoth- 



