54 THE ACTIVE FORCES OF LIVING ORGANISMS 

 Electricity In the physiological effects to which we have 



as au 



almost alluded electricity plays a, comparatively speaking, 

 agency, neutral part, that chiefly of an intermediary. This, 

 moreover, is entirely in accordance with the theory 

 already advanced, that electricity is a mode of motion 

 of the ether ; that the latter acts as a go-between 

 transmitting force, the kind of which depends on the 

 nature of the various forms of matter from which 

 it proceeds ; and, lastly, that electrical potential is 

 due partly to the tension natural to the ether, and 

 partly to the action of excited groups of molecules 

 and atoms upon the ether, which, becoming imbued 

 with their special vibratory character, convey it to 

 other atoms and molecules, the attractive and repul- 

 sive power of one electrified substance for another 

 being thus evolved. 

 The effects The nature of the air we breathe is universally 



of high . . . 1 n • n 



altitudes, recogniscd as exercismg a most marked mnuence 

 on the nutrition of the body, and from time to time 

 during the past century the subject has been 

 approached from the point of view of the effect 

 produced by residence at various altitudes. After 

 De Saussure, it was handled with great ability by 

 that much-abused French physiologist, Paul Bert ; 

 and quite recently an important work* by Mosso has 

 appeared, whose opinions in regard to some essential 

 points are at variance with those of the latter. 



According to Plammarion, the pressure of the atmo- 

 sphere at 2,600 metres above sea-level is diminished 

 * ' Der Mensch auf den Hochalpen.' 



