PRELIMINARY. 



IN THE first section of this book I have endeavored 

 to show that variation of character is not promis- 

 cuous or multifarious, but that it is limited to certain 

 definite directions. That this rule applies to all kinds 

 of characters, whether they are of the less fundamen- 

 tal kind which distinguish species, or of the more fun- 

 damental kind which distinguish the higher divisions. 



In the second section I have endeavored to show 

 that many characters, both those of the more super- 

 ficial and those of the profounder kinds, are the direct 

 result of chemical and physical stimuli, and of molar 

 motion or use, or of the absence of the latter or dis- 

 use. 



It now remains to ascertain whether the characters 

 or variations so produced are inherited : that is, whether 

 characters so acquired are transmitted to succeeding 

 generations. Unless this proposition is demonstrated, 

 our knowledge of the method of evolution remains in- 

 complete, and we must look for some new explana- 

 tion of the progressive increments and decrements of 

 structure which constitute the history of organic life. 

 The present part of this book will be devoted to an 

 examination of this question, and to the exposition of 

 such laws as may be derived from such examination. 



