118 



Infusoria and rotatory animals. Their propagation 

 can be observed and obtained ad libitum in a room. 



The equivocal generation has only reason in its 

 favour and a very limited sphere of observations, 

 owing to the excessive difficulty of observing such 

 infinitely small creatures. 



Propagation by sexual generation and by the for- 

 mation of offsprings , has in its favour the greater 

 mass of observations: which observations are positive 

 in this case, and seconded by the form, appearance 

 and size of these beings. The necessary conditions 

 to these two modes of generation can be expressed 

 by the following formule: 



GENERATIO AEQUIVOCA. 

 SPONTANEOUS GENERATION. 



GENERATIO SECUNDARIA. 

 SEXUAL GENERATION. 



