SOURCE OF ORGANIC ENERGY. 29 



fications in the form and nature of that motion to 

 other sources ; namely, the external forces acting 

 upon the body from various directions. 



These two sets of forces, the internal and the ex- 

 ternal, are not the only factors which determine the 

 ultimate form of bodies, —another and very impor- 

 tant factor is the nature of the substance of which 

 they are composed, whether it be rigid, or elastic, 

 solid, liquid, or viscous. 



In order to understand the phenomena of living 

 matter as a display of physical forces, we must take 

 the most comprehensive view of the action of forces 

 upon matter in general, — the inanimate as well as 

 the animate. We must take note not only of those 

 effects which are made evident by experiment, but 

 also of those which are rendered probable by deduc- 

 tion, — remembering that in the apparent dissipation 

 of a force, even after it has escaped the observation 

 of our senses and the analysis of our instruments, it 

 still acts undestroyed — in a state where we can fol- 

 low it only with our imagination. We must dismiss , 

 from our minds all ideas of motionless, changeless 

 matter, and picture to ourselves a universe where 

 nothing is at rest, where every atom is quivering in 

 ceaseless vibration, where each minutest particle of 

 matter is held in its line of motion through space, by 

 the action of opposing forces, pulled now this way. 



