52 THE HUMAN MOTOR 



The problem of mysterious energies of the organism leads to that 

 of inter-cellular reactions of these varieties and of the obscure laws 

 by which they are regulated. The resistance of living animals to 

 depressing, pathogenic and toxic conditions induced the earlier 

 physicians to hypothecate the existence of a " vital force" either 

 in the blood or in the nervous system. A little of this doctrine, 

 and a little of the belief in the soul combined to decide certain 

 minds in favour of a special energy in the human being which 

 they termed a survival of the divine breath. 



To-day those gratuitous hypotheses are superseded by the 

 theory of radioactivity, which manifests itself in solid, liquid or 

 gaseous matter. The fact that a single trace of. radioactive sub- 

 stance emits, almost indefinitely, luminous, thermal or electric 

 energy, leaves the door open to a radioactive theory of thought 

 according to which the nervous matter dissociates or disengages 

 itself in such a manner as to develop intellectual energy. 



Positive science cannot embrace such suppositions. Without 

 doubt it has been found f 1 ) that the tissues of man are radio- 

 active, that the brain exhibits even special activity. But the 

 phenomenon is connected with nutrition, which enriches the 

 organism with radioactive elements. Also it is said that old 

 subjects have a superior intensity to that observed in the young. 

 Death does not end that radioactivity, although all thought has 

 disappeared. Therefore it is as well to reserve one's opinion on 

 these difficult and uncertain problems. Lastly, in regard to the 

 action of nervous organs, one is constrained to admit that an 

 unknown form of energy emanates from them, which cannot be 

 measured in calories and which, in consequence, escapes us. 

 Nervous energies, which were once upon a time called " nervous 

 fluids," after having been the " animal spirits " of the Cartesian 

 school, act in the functions of the animal like the priming of a gun. 

 They release the machinery whose work is incommeasureable 

 by any calorimetric valuations. 



39. Loss of Energy, Passive Resistance. Natural phenomena 

 all tend to transform the energies into one of their single 

 forms, namely, heat, which it is a destructive change. Thus 

 animal organism loses all its chemical energy as heat, if it is in 

 repose, but if it produces mechanical work, this will be taken 

 from free energy, everything else being lost as heat. 



In the movement of solid bodies, a similar loss, more or less 

 violent, always takes place, seeing that indeformable and perfect 

 solids do not exist. The parts of machines being deformed a 

 little at points of contact, there is as a result external friction of a 

 vibratory nature, in consequence of which there is a dissipation 



() R. Werner, Munch. Med. Wochenschrift, No. 1 (1906) ; A. Caan, 

 $itzungsber d. Heidelb. Akad. d. Wissensch., Mim. v. (1911). 



