626 THE POPULAR SCIENCE MONTHLY. 



the doctrine, and belonged rather to the way of conceiving that the 

 evolution of organisms has taken place. Looking not for differences 

 but relationships among organisms, I thought I saw that a simple and 

 general law had governed their formation, that they were derived one 

 from another by a constant procedure, and I found myself adding fur- 

 ther arguments to the theory of the genealogical origin of species. 

 The law which I now have to put forward may be called the law of 

 association ; and the process by which it works, the transformation of 

 societies into individuals. 



When we have proved that all living beings are composed of mi- 

 croscopic corpuscles more or less alike, when we see such corpuscles 

 capable of leading an independent life constituting by themselves the 

 simplest organisms, it occurs to us to compare the higher animals and 

 vegetables to vast associations of distinct individuals, each represented 

 by one of these corpuscles or cells. In the same animal the cells as- 

 sume many different forms, having different physiological properties. 

 These forms and properties are not modified by the vicinity of differ- 

 ent cells. Within the organism each cell lives as if it were alone. If 

 it were possible to isolate a cell of the human body and surround it by 

 normal nutritive material, it would continue to live, to develop and 

 reproduce itself, and carry on all its physiological functions exactly as 

 before. Further, in the organism itself, the life of each cell is so inde- 

 pendent of that of its neighbors, that we may kill all the cells of one 

 kind without injuring the others. Claude Bernard has proved that 

 curare poisons the elements that terminate the motor nerves, thus 

 abolishing all movement without injuring any other part of the sys- 

 tem and leaving sensation intact. These researches led him to the 

 principle of the independence of the anatomical elements. Not only 

 are the elementary individuals of organisms sometimes very dissimi- 

 lar, but they preserve their personality, live their own way, and keep 

 up with their fellow citizens the relations of good neighborhood. We 

 may compare an animal or plant to a populous town, where each per- 

 son practices a particular industry on his own account, and yet helps 

 the general prosperity through the activity of exchange. In high or- 

 ganisms, a special corporation in ceaseless movement is the medium 

 of these exchanges. The blood-globules are true traders, taking along 

 in the liquid where they swim the complex merchandise in which they 

 deal. 



Just as we had employed all the comparisons that pedigree fur- 

 nishes to express the likenesses among organisms before supposing 

 them really to be blood relations, so we have compared organisms to 

 societies and societies to organisms, all the while regarding these com- 

 parisons as mere fancies. On the contrary, in the last year, we have 

 reached the conclusion that association has played an important if not 

 exclusive part in the development of organs. We find convincing 

 proof of this in the history of Polyps and of Worms. The connection 



