II OF THE NATURAL HISTORY SCIENCES 41 



place. But after a time the effects of this disturb- 

 ance will subside equilibrium will be restored, 

 and the water will return to its passive state. 



Expose the water to cold it will solidify and 

 in so doing its particles will arrange themselves 

 in definite crystalline shapes. But once formed, 

 these crystals change no further. 



Again, substitute for the lump of gold some 

 substance capable of entering into chemical rela- 

 tions with the water: say, a mass of that sub- 

 stance which is called " protein " the substance 

 of flesh : a very considerable disturbance of 

 equilibrium will take place all sorts of chemical 

 compositions and decompositions will occur ; but 

 in the end, as before, the result will be the re- 

 sumption of a condition of rest. 



Instead of such a mass of dead protein, however, 

 take a particle of living protein one of those 

 minute microscopic living things which throng our 

 pools, and are known as Infusoria such a creature, 

 for instance, as an Euglena, and place it in our 

 vessel of water. It is a round mass provided with 

 a long filament, and except in this peculiarity of 

 shape, presents no appreciable physical or chemical 

 difference whereby it might be distinguished from 

 the particle of dead protein. 



But the difference in the phenomena to which 

 it will give rise is immense : in the first place it 

 will develop a vast quantity of physical force 

 cleaving the water in all directions with consider- 



