cial, by which the particles of liquid or gaseous bodies are 

 converted into crystal or solid bodies of regularly limited 

 form." 



Matter can not exist in solids, and at the same time in 

 liquid or gaseous forms — so that the quantity of mobile 

 matter must have decreased by the amount thus used. 



The same truth applies yet more strikingly in the pro- 

 cess of respiration, and not only of respiration but of ali- 

 mentation. 



All organic life is entirely dependent upon the mobile 

 elements of matter. The atmosphere and waters have 

 hitherto been considered rather as the media of life than 

 as the very material from lohich all organic life has been and 

 is made up. So absolutely necessary is water to all organic 

 development, that it is supplied in many different ways, 

 and in apparently inexhaustible quantities. It is the very 

 food of animals as well as vegetables — nor is this any the 

 less true because small portions of other elements are 

 used with it, and absolutely necessary to its being able 

 properly to develop organized bodies. 



The mobile elements of matter have been consumed by 

 every organism, from the foraminifera that fed upon the 

 warm waters of the primeval ocean to the air-breathing 

 and aquatic creatures that swarm the air, the earth and 

 waters to-day. 



The whole living creation holds such matter in solid forms 

 now — ^having lost none of the organic elements of which 

 it is composed. Of the quantity of this matter no idea can 

 be formed, except by reflecting upon the universality of 

 life. The earth, the water, and the air teem with living 

 germs and organisms. The larger forms of the animal 

 creation, and the great masses of vegetation, especially in 

 the tropics, strike the eye by their immensity and extent. 

 But as throughout all nature the ideas of comparison be- 

 tween great and small are continually confounded, so when 

 we contemplate the immense extent and quantity of micro- 



