548 POPULAR SCIENCE MONTHLY 



beginning; thus a too susceptible organism would quickly be thrown 

 out of gear and would perish; a too conservative one, unless adapted 

 to practically unchanging types of life, would equally perish. There 

 would be a certain optimum susceptibility, which would be preserved, 

 and would differ for different groups. More than this, certain kinds 

 of susceptibility would be favored, and being once developed might, 

 like bad habits, become harmful through the accumulation of results, 

 resulting in extinction. Thus rapid evolution would usually go with 

 a high percentage of failures, and a considerable number of grotesque 

 forms, such as we see among the vertebrates. According to this view, 

 the initiation of any evolutionary trend, except the oscillatory move- 

 ments above described, would be exceedingly slow, and quite beyond 

 the reach of experimental methods, other than those furnished by 

 nature in the course of ages; hence, as Osborn has indicated, the great 

 importance of paleontological researches. At the same time, while the 

 processes which change the fundamental character of animals and 

 plants may be too slow to observe, it is not to be doubted that very 

 much light may be obtained by the experimental method, if only by 

 way of showing us what it is that has been evolved — a thing we seem 

 not to have clearly known. If the control of orthogenetic changes is 

 reserved, as it were, for the gods — and we, doubtless, should only make 

 a mess of it — we may be well satisfied if we can take advantage of the 

 oscillation processes, which experimental researches are showing to be 

 far more extensive and much easier to control than had previously been 

 suspected. 



