568 EHRENBERG ON ORGANIC MOLECULES AND ATOMS. 



observed in nature, and surpasses by far that of insects, yet it does not 

 by a vast deal reach that of the polygastrical infusoria. In Paramcc- 

 cium Aurelici, which is about -^^ of a lin. in size, and which I observed 

 with certainty during several days of a long duration of life, I have 

 seen within twenty-four hours, by simple horizontal division, the oc- 

 tuple increase of one individual, which would allow the possibility of the 

 double of that increase. As however these animals increase not only 

 by separation but also by eggs, and secrete these eggs not singly but 

 in masses, and besides in addition to these form buds, we have such a 

 possible immense increase of a single individual in forty-eight hours, 

 that we may leave off counting and speak of innumerability*. 



Who now under such circumstances can wonder if within the space of 

 two or three days fluids swarm with such animals ? Is it not more natural 

 towonderhowitisthat often it does nothappen? We no longer now require 

 a generatio cequivoca to explain these phasnomena; they belong to those 

 Avithin the reach of experience and observation ; and where anything 

 astonishing of this kind may occur, the observer must take great care 

 that the fault of superficialness be not laid to him. If therefore I 

 supposed in my first paper that the generatio cequivoca of infusoria 

 might still be ascribed to their eggs, it now appears to me from obser- 

 vations on the development and increase of individuals, that the neces- 

 sity of such an hypothesis, and even its probability, must vanish. I 

 now indeed believe that the generatio primitiva may as an ever- 

 existing subject of experience have undergone its mortal combat. Upon 

 this subject however I cannot undertake to solve all the problematic 

 })oints relative to it, of which there are many and important ones, par- 

 ticularly in relation to geology, as they are generally s^ibjective, and 

 but rarely objective; but I wish here to urge the consideration of the 

 indefinitely small, as a main position for all branches of natural history, 

 from which perhaps at a subsequent period I may also develop my 

 more special views. 



11. On Atoms and Molecules as subjects of experience. 



Atomic philosophers have of late years, partly by their ingenious 

 tlieories for the explanation of the phaenomena of light, and partly by 

 their ingenious as well as fertile atomic calculations of the doctrine of 

 porportions in chemistry, obtained an undeniable practical superiority 

 over dynamists, how much greater soever the satisfaction and recom- 

 pense of the latter may seem to themselves to be ; and hence it has 

 happened that in the doctrine of the smallest particles of bodies we 



* This rapidity and great capability of increase of the iiifusovia might also bo 

 worthy the attention of analysing chemists, as they might qnickly produce a great 

 influence on organ'c substances, namely on some colouring substances. Eoiling 

 heat, or a few drops of alcohol, precipitate the infusoria, and they may tlicn be 

 removed as slime with certainty by filtration. It is necessary to operate quickly. 



