OEGANIC EVOLUTION RECONSIDERED. 



Admitting that the theories of the leading writers on the 

 subject have advanced us on the way to more complete views of 

 the mode of origin of the forms of the organic world, it must 

 stm be felt that all theories yet propounded fall short of being 

 entirely satisfactory. It seems to us unfortunate that the sub- 

 ject has not received more attention from physiologists, as 

 without doubt, the final solution m.ust come through that sci- 

 ence which deals with the properties rather than the forms of 

 protoplasm. ; or, ia other words, the fundamental principles 

 underlying organic evolution are physiological. But, in the 

 unraveling of a subject of such extreme complexity, all sciences 

 must probably contribute their quota to make up the truth, as 

 many rays of different colors compounded form white light. 

 As with other theories of the inductive sciences, no^ can be 

 more than temporary ; there must be constant modification to 

 meet increasing knowledge. Conscious that any views we our- 

 selves advance must sooner or later be modified as all others, 

 even if acceptable now, we venture to lay before the reader the 

 opinions we have formed upon this subject as the result of con- 

 siderable thought. 



All vital phenomena may be regarded as the resultant of 

 the action of external conditions and internal tendencies. Amid 

 the constant change which like involves we recognize two 

 things : the tendency to retain old modes of behavior, and the 

 tendency to modification or variation. Since those impulses 

 originally bestowed on matter when it became living, must, in 

 order to prevail against the forces from without, which tend to 

 destroy it, have considerable potency .-the tendency to modifica- 

 tion is naturally and necessarily less than to permanence of 

 form and function. 



From these principles it follows that when an Amoeba or 

 kindred organism divides after a longer or shorter period, it is 



