THE BEGINNINGS OF LIFE 



blood comes rushing through a capillary tube, 

 and certain compound molecules of albuminous 

 matter are taken from it and retained by the 

 adjacent tissue, then, according to the vitalistic 

 theory, the " vital principle " is at work. Dur- 

 ing life this " principle " continues to work ; 

 but at death it leaves the organism, which is 

 then given up to the mercy of physical forces. 

 Such was the theory of life which was held by 

 many physiologists even at a time within the 

 recollection of persons now living ; and it doubt- 

 less still survives in minds uninstructed in mod- 

 ern science. So long as this doctrine held un- 

 disputed sway, the belief that all life proceeds 

 from life was not likely to be seriously im- 

 pugned. For whence, save by derivation from 

 some other " principle " like unto itself, could 

 this mysterious " vital principle " arise ? Be- 

 sides all this, the Doctrine of Evolution had 

 not yet been originated ; all things were sup- 

 posed to have been created at once in their 

 present condition ; and, as no need was felt of 

 explaining scientifically the origin of the highest 

 organisms, so there was no disposition to in- 

 quire into the origin of those lowest in the scale. 

 A series of separate creative acts was supposed 

 to account for the whole. 



Strengthened by these metaphysical concep- 

 tions, the doctrine omne vivum ex vivo remained 

 in possession of the field for two centuries. 



345 



