INTRODUCTION. 



13 



evolution appear fortuitously, and those which are 

 beneficial survive by natural selection, v/liile those 

 which are not so, disappear. Characters both benefi- 

 cial and useless or harmless, which are acquired by the 

 adult organism, are not transmitted to the young, so 

 that no education in habit or structure acquired by the 

 adult, has any influence in altering the course of evo- 

 lution. This is the doctrine of Preformation. From 

 this point of view the cause of the variations of organ- 

 isms has yet to be discovered. 



The other point of view sees in variation the direct 

 result of stimuli from within or without the organism ; 

 and holds that evolution consists of the inheritance of 

 such variations and the survival of the fit through nat- 

 ural selection. This is the doctrine of Epigenesis. To 

 this I would add that in so far as sensations or states 

 of consciousness are present, they constitute a factor m 

 the process, since they enable an organism to modify 

 or change its stimuli. The position of each of these 

 schools on each of the questions to which reference 

 has been made, may be placed in opposition as follows : 



1. Variations appear in defi- 

 nite directions. 



2. Variations are caused by 

 the interaction of the organic 

 being and its environment. 



3. Acquired variations may 

 be inherited. 



4. Variations survive directly 

 as they are adapted to changing 

 environments. (Natural selec- 

 tion.) 



I. Variations are promiscu- 

 ous or multifarious. 



2. Variations are "congeni- 

 tal " or are caused by mingling 

 of male and female germ-plas- 

 mas. 



3. Acquired variations cannot 

 be inherited. 



4. Variations survive directly 

 as they are adapted to changing 

 environments. (Natural selec- 

 tion.) 



