ILLUSTRATED AMONG PROTOZOA. 103 



course of its unceasing development. Suppose 

 the vertebrates to be descended from worms, then 

 in like manner the co-ordination of forces necessary 

 to produce a worm must have been acquired, and 

 so on, back to the simplest form of living matter. 

 The raw energy, and matter in a crude state, we 

 may suppose to have existed anywhere at any time, 

 but the co-ordinations of forces necessary to pro- 

 duce a vorticella, a worm, a fish, or a horse, have 

 been acquired by the primitive form of living 

 matter by a long and slow process. It must have 

 been a series of causes and effects according to 

 laws, with no fortuitous variations, — a process that 

 acted in the living continuity of organic matter, 

 without regard to the destruction of the "unfit" 

 or the lopping off of side-branches of development. 



This constant acquirement of new co-ordinations 

 of directive forces, indicates a universal capacity 

 of development, showing itself at every step in the 

 long course of evolution and co-extensive with life 

 itself. This capacity is that which makes possible 

 every new variation and every advance in develop- 

 ment. We are compelled to believe that it was 

 present in the archaic protoplasm, the first living 

 matter on the globe, just as much as in the living 

 forms of to-day. If we seek to know this capacity 

 in other terms, we can only ascribe it to the un- 



