i88i.J 
Latent Heat. 
645 
ganic chemism was very active upon the earth, and doubtless 
very energetic displays of motive force took place. Now 
inorganic chemical activity has almost ceased to exist, and 
organic chemism has taken its place. But to the full deve- 
lopment of organic adtion violent and irregular displays of 
force are very adverse, and we find that organic life has 
advanced to higher and higher forms in proportion as the 
energy of inorganic adtion decreased. When complete regu- 
larity in material conditions and changes takes the place of 
the present irregularity, organic life may reach its highest 
development, while not only inorganic adtivity may cease to 
exist, but also the lower stages of organic adtivity. This 
seems the tendency of chemical change, and we have war- 
rant, therefore, to look forward to a period in which all free 
energy will be exerted in the produdtion of living forms, the 
only adtive inorganic agencies being those necessary to the 
produdtion of vegetable forms. 
For such a result it is not necessary that the kinds and 
conditions of matter, and degree of temperature, shall con- 
tinue precisely as they exist at present upon the earth. 
Nature may have far more versatility in this respedt than 
she is usually credited with. Thus in the produdtion of 
terrestrial organic life just such materials are used as are 
most available, the gaseous carbon and oxygen, and the 
liquid water and ammonia. Of the solid constituents of the 
earth only those are employed which are widely diffused and 
readily soluble. Thus organic life employs here all the ma- 
terial which is in a condition adapting it to chemical adtion, 
and in quantities closely conformable to the chemical adtivity 
and availability of each element. And one element is fre- 
quently replaced by another when the latter becomes more 
available. 
As it is possibly unimportant what materials take part in 
organic integration so that their physical condition is such 
as to adapt them to adtive chemical change, so it may be 
unimportant what the ruling temperature is, if it be only 
such as to preserve matter in this necessary physical condi- 
tion, and to excite its chemical adtivity. On other spheres 
than the earth life may flourish under widely different con- 
ditions, both as to material and to temperature. And finally 
it is unimportant whence comes the energy employed in 
organic chemism. On the earth the energy of the solar 
beams is employed, this being the most available and 
vigorous source of motive energy. But elsewhere heat force 
arising from local sources might be employed ; and if this 
energy were applied diredtly and wholly to the furtherance 
