The Message of Science. 15 



the teeth of a gigantic resistance. The energy in proto- 

 plasm is largely expended in overcoming this molar 

 resistance ; the bulk of our living substance has neces- 

 sarily been impressed into mechanical service, — bone, 

 teeth, hair, cuticle, muscle, tendon, in order to make way 

 and obtain food. This, in fact, is life on earth, as man 

 has thus far led it ; but it is possible to improve the earth 

 as a theater of life, and by the control and regulation of 

 its " natural forces " to lessen the resistance. 



Growth is a law of living matter; and on the earth's 

 surface protoplasm is capable, under ordinarily favorable 

 circumstances, of increasing its bulk much more rapidly 

 than it wastes, or dies. 



It is able to conserve energy. A cell is capable of 

 raising up a greater amount of non-living matter into the 

 living condition than it loses from the living condition by 

 the act of so doing. 



The only limit to such growth is the capacity of the 

 earth as a field for life; it constantly sustains as much 

 matter in the living condition as it has room for. The 

 various genera and species of living things, moreover, 

 mutually limit and restrict each other. But for animals, 

 plants would probably overrun the earth to the full ex- 

 tent of its standing room ; but for some species of animals, 

 others would increase inordinately. Bacteria, in a favor- 

 able medium, propagate at a rate of which no conception 

 can be given in figures. 



