174 GENEEAL EVOLUTION. 



lution. Nevertheless the present time is pre-eminently one of 

 generalization in this field, and properly so. Facts have been ac- 

 cumulating for a long period, and are now sufficiently numerous 

 to yield important results, under proper classification and induc- 

 tion. Darwin led the way in this work, and the development 

 hypothesis is regarded as demonstrated by most biologists. The 

 discussion of the laws of its progress involves a multitude of 

 subordinate hypotheses. In the following essay, these are ar- 

 ranged under five prominent heads, viz. : 1. The law of Accelera- 

 tion and Eetardation; 2. The law of Kepetitive Addition; 3. The 

 law of Use and Effort ; 4. The law of Grade Influence ; 5. The 

 law of Intelligent Selection. Of these, the first and second are 

 regarded by the author as demonstrated, the third and fourth as 

 only reduced to a partial demonstration, while the fifth is a con- 

 sequence of the third, and stands or falls with it. 



The discussion of this subject divides itself into two parts, 

 viz. : a consideration of the proof that evolution of organic types 

 or descent with modification has taken place ; and, secondly, the 

 investigation of the laws in accordance with which this develop- 

 ment has progressed. As the latter involves the use of the evi- 

 dence included in the former, I will not devote a special chapter 

 to the proof for evolution. 



The influences and forces which have operated to produce the 

 type structures of the animal kingdom have been plainly of two 

 kinds: 1. Originative; '^.Directive. The prime importance of 

 the former is obvious ; that the latter is only secondary in the 

 order of time or succession is evident from the fact that it con- 

 trols the preservation or destruction of the results or creations of 

 the first, and thus furnishes the bases of the (exhibitions of the 

 originative forces in the production of the successive generations 

 of living beings. 



Wallace and Darwin have propounded as the cause of modifi- 

 cation in descent their law of natural selection. This law has 

 been epitomized by Spencer as the ''survival of the fittest." 

 This neat expression no doubt covers the case, but it leaves the 

 origin of the fittest entirely untouched. Darwin assumes a 

 "tendency to variation" in nature, and it is plainly necessary to 

 do this, in order that materials for the exercise of a selection 

 should exist. Darwin and Wallace's law is, then, only restrictive, 

 directive, conservative, or destructive of something already created. 

 I propose then to seek for the originative laws by which these sub- 



