ON THE CAUSES OF ORGANIZATION. 543 



not be preferable, in such investigations, to take 

 for our guides patient experiment and cautious 

 observation ? They may not carry us so far or so 

 fast as many will in general be inclined to go ; 

 but, so far as they conduct us, they will do it on 

 certain and on safe grounds. Inquiring at them, 

 they give us no information whatever respecting 

 any previous existence of plants or animals float- 

 ing invisibly through the regions of space, in the 

 state of infinitely minute organized atoms : 

 They only inform us, that the first materials out 

 of which organized structures are formed, are 

 fluids secreted from the vessels of the parents, 

 and that something operating within these fluids 

 begins to arrange them into systems of organs 

 similar to those belonging to the species of 

 the individuals that supply the materials, and 

 that this something, continuing to operate on 

 the same plan, making always a selection of what 

 is useful, and rejecting what is hurtful, arranges 

 the materials that are afterwards supplied from 

 the food and drink, and the air that is inspired, 

 till the organs be completed : That the system 

 of organs thus formed, is the medium of inter- 

 course between it, and surrounding objects ; so 

 that they are found mutually to re-act upon one 

 another : That in some animals, when powerfully 

 excited, it employs a part of these organs to de- 

 stroy the rest ; and often, when the organs are de- 

 ficient or injured, or in a state which it cannot re- 



