CCi THE EVOLUTION OF LIFE. 



Chicago. Out of these the reader may form a notion of the 

 theory : 



&quot;Orthogenesis shows that organisms develop in definite directions 

 without the least regard for utility through purely physiological causes 

 as the result of organic growth, as I term the process.&quot; 



&quot; I am concerned in this paper with definitely directed evolution 

 as the cause of transmutation, and not with the effects of the use and 

 activity of organs which with Lamarck I adopted as the second main 

 explanatory cause thereof.&quot; 



&quot; The causes of definitely directed evolution are contained, accord 

 ing to my view, in the effects produced by outward circumstances and 

 influences such as climate and nutrition upon the constitution of a 

 given organism.&quot; 



&quot;At variance with all the facts of definitely directed evolution 

 ... is also the contention of my opponent [Weismann] . . . 

 that the variations demonstrably oscillate to and fro in the most di 

 verse directions about a given zero-point. There is no oscillation in 

 the direction of development, but simply an advance forwards in a 

 straight line with occasional lateral divergences whereby the forkings 

 of the ancestral tree are produced. &quot; * 



These sentences contain one of those explanations which 

 explain nothing; for we are not enabled to see how the 

 &quot; outward circumstances and influences &quot; produce the effects 

 ascribed to them. We are not shown in what way they 

 cause organic evolution in general, still less in what way 

 they cause the infinitely-varied forms in which organic evo 

 lution results. The assertion that evolution takes definitely- 

 directed lines is accompanied by no indication of the reasons 

 why particular lines are followed rather than others. In 

 short, we are simply taken a step back, and for further in 

 terpretation referred to a cause said to be adequate, but the 

 operations of which we are to imagine as best we may. 



This is a re-introduction of supernaturalism under a dis 

 guise. It may pair off with the conception made popular by 

 the Vestiges of the Natural History of Creation, in which it 

 was contended that there exists a persistent tendency towards 

 the birth of a higher form of creature ; or it may be bracketed 

 * &quot; On Orthogenesis and the Impotence of Natural Selection in Species- 

 Formation,&quot; pp. 2, 19, 22, 24. 



