6o8 THE BEGINNINGS OF LIFE. 



How high in the scale, either of plant or of animal 

 life, any extreme degree of variability will extend, we 

 cannot at present say, although we are entitled to 

 expect that it will gradually diminish in extent as the 

 complexity of organization increases \ It may well 

 be, that after even comparatively rudimentary degrees 

 of organization have been evolved, a condition of 

 comparatively stable moving equilibrium is attained, 

 so that — the conditions of life remaining the same — the 

 organism may no longer present anything more than a 

 mere dwarfed tendency to further differentiation 2. Its 

 internal tendencies may have more or less satisfied 



work : — • During early periods of the earth's history, when the forms of 

 life were probably fewer and simpler, the rate of change was probably 

 slower ; and at the first dawn of life, when very few forms of the simplest 

 structure existed, the rate of change may have been slow in an extreme 

 degree.' Now, although such views are quite consistent with Mr. Dar- 

 win's exaggerated belief in the all-powerful efficacy of Natural Selection 

 as a producer of change, they are wholly opposed to the almost universal 

 observation of naturalists, and just as antagonistic to the legitimate 

 a priori deductions of the Evolution philosophy. 



^ See Herbert Spencer's 'Principles of Biology,' vol. i. pp. 192-200. 



2 Such organisms may, however, become more amenable to the modi- 

 fying influence of changes in external conditions at periods when their 

 vitality is temporarily lowered — just as a top may be made to totter by 

 a s.ight touch when its axial rotations are becoming slow, though it 

 would have been apparently unaffected by a similar touch made at a 

 time when it was spinning rapidly. Rapid growth indicates rapid mole- 

 cular movements in the things which grow. In the more putrescible 

 infusions the molecular movements are probably extremely rapid ; enor- 

 mous quantities of Bacteria are quickly produced, which, owing to their 

 frequent fission, seem never to grow or increase in size. It is almost 

 impossible to modify the forms which appear in such a solution. [See 

 pp. 137 and 502.) 



