30 GENERAL PROPERTIES OF LIVING TISSUES 



degrees of violence, and it is probable that even at 

 low temperatures some of the encounters are so 

 violent that one or both of the compound molecules 

 are split up into their constituents. Each of these 

 constituent molecules now knocks about among 

 the rest till it meets with another molecule of 

 the opposite kind, and unites with it to form a 

 new molecule of the compound. In every com- 

 pound, therefore, a certain proportion of the 

 molecules at any instant are broken up into their 

 constituent atoms. 



" Now Clatisius supposes that it is on the con- 

 stituent molecules in their intervals of freedom 

 that the electromotive force acts, deflecting them 

 slightly from the paths they would otherwise 

 have followed, and causing the positive constit- 

 uents to travel, on the whole, more in the positive 

 than in the negative direction, and the negative 

 constituents more in the negative direction than 

 in the positive. The electromotive force, there- 

 fore, does not produce the disruptions and reunions 

 of the molecules, but, finding these disruptions 

 and reunions already going on, it influences the 

 motion of the constituents during their intervals 

 of freedom." 1 



1 Quoted from Clerk Maxwell by Walker in his admirable 

 "Introduction to Physical Chemistry," a book to which the 

 present writer is much indebted. 



