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 equi- 

 librium will take place — all sorts of chemical com- 

 positions and decompositions will occur; but in 

 the end, as before, the result will be the resump- 

 tion of a condition of rest. 



Instead of such a mass of dead protein, how- 

 ever, 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 pro- 

 vided with a long filament, and except in this pe- 

 culiarity of shape, presents no appreciable physical 

 or chemical difference whereby it might be distin- 

 guished from the particle of dead protein. 



But the difference in the phaenomena to which 

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

 will develop a vast quantity of ph3'sical force — 

 cleaving the water in all directions with consider- 



