152 VITALISM AND SCHOLASTICISM 



In other cases the gas-bubbles, instead of 

 being confined to one part ,of the body, are 

 generally disseminated throughout it. The 

 consequence of this is that the entire organism 

 becomes sufficiently light to float to the top 

 of the water in which it is immersed. There 

 it is able to assume the position which it 

 desires. 



Such a purposive action as this is wholly 

 different from the actions of chemical sub- 

 stances or of those which we study in the 

 physical laboratory. 



Forces of this latter kind look backward, 

 not forward, for their explanation. They are 

 the result of what has been and the end of the 

 series of occurrences is an equilibrium. 



Let us take an example. Suppose we add 

 oil of vitriol sulphuric acid to a piece of 

 carbonate of lime. There will be profuse 

 effervescence, due to the breaking up of the 

 union between the carbonic acid and the lime 

 and the giving-off of the former in the shape 

 of gas. After a time this will cease and all 

 the carbonic acid gas having been got rid of, 

 sulphate of lime or gypsum will remain in the 

 receptacle in which the mixture was made. 

 Now all these thing are explained by the 

 bringing together of the sulphuric acid and the 

 carbonate of lime, since the former having a 



