THE ANIMAL KINGDOM. 41 



some other naturalists as organic molecules, the agglomera- 

 tion of which, presided over by fixed laws, contributed to 

 the formation of plants and animals. After the time of the 

 immortal overseer of the Jardin du Roi, Oken upheld the 

 same opinion, maintaining that large animals were aggre- 

 gates of monads ; an idea which, as the reader will perceive, 

 seems to be only a repetition of the famous hypothesis of 

 atoms, which we owe to Leucippus, wnich, after having 

 flourished in antiquity, is seen shedding its latest gleams of 

 light upon the writings of Kepler and Descartes. 1 



These monads, which are simply living atoms, are so ex- 

 tremely small that they can only be seen by the help of 

 the greatest magnifying power. 

 They are met with in all kinds 

 of animal and vegetable infu- 

 sions, and their number is often 

 so prodigious that they all seem 

 to touch each other in the drop 

 of liquid in which they move ; 

 it is astonishing to see that they 

 do not stifle one another. A 



, , . . 20. Monads. 



single drop sometimes contains 



more of them than there are inhabitants upon the globe. 

 These animalcules are often mere shells, and show no in- 

 ternal organization ; but in some of them Ehrenberg re- 



1 The supporters of the famous atomic system, which played such a great part 

 in hoth ancient and modern philosophy, maintained that the ceaseless production 

 of planets and of all the living creatures on them was due to the fortuitous con- 

 course of atoms. Leucippus, and even more Epicurus, brought this system into 

 vogue. Though defended by Kepler, Descartes, and Gassendi, modern science 

 has completely overthrown it. 



