152 INTRODUCTION TO SCIENCE 



an infinity of little partial views of the act, but 

 what one needs for an explanation of the fact is 

 a comprehensive view which will unite all the 

 relevant features of it into one picture. To the 

 chemist confronted with this problem there is no 

 fact of migration at all, there is only an intricate 

 enravelment of chemical reaction; to the biolo- 

 gist the fact of migration to a particular region 

 for a particular purpose is cardinal, and the 

 chemical processes involved in the action are 

 negligible." 



But if the mechanistic account of the eel's 

 migration fails, is the vitalistic one any better? 

 Let us think of this for a little. The aim of biol- 

 ogy is not to give ultimate explanations, but to 

 render biological phenomena intelligible; and 

 that means to obtain general conceptions as to 

 their nature. We explain a thing biologically 

 when we relate it to some general fact or formula 

 of living things. 



Therefore if pressed to make the story of the 

 eel less of a curiosity, we should ask to be allowed 

 to start with the concept of an organism with 

 certain at present irreducible qualities one of 

 the biggest of which is simply that it is an histori- 

 cal being. It is determined by the past its own 

 past and the past of its race. Its inheritance is 

 a treasure-store of the ages. Non-living things 

 have no history in the biological sense. The 



