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incisions, grow angulous, sharp and pointed. When 

 the young animalcule has attained the size and form 

 of the maternal part, the union continues still some 

 time, and is soon separated, whilst the female ani- 

 malcule advances towards death and dissolution , to 

 repeat the above described process , and propagate 

 in this manner its genus and species. 



After having described the propagation of these 

 animalcules , such as we have observed it , we shall 

 venture to say a few words, upon the question of 

 aequivocal generation, which has been in our days a 

 subject of so much controversy. 



Reason speaks in its favour; I might almost say, 

 acknowledges it, but the most direct and impartial 

 observations seem to be in contradiction with it. 



The water I put in contact with pure organic 

 matter, w r ith full certainty that no egg nor animal- 

 cule could have been mixed to them, and abandoned 

 to putrefaction, has generated nothing, during 4 8 

 months, except polygaslric Infusoria, some species 

 of Monas and Colpoda, small Vorticellae , and very 

 seldom a little Vibrio (Anguillula Ehrenb.). 



The Naviculae, the Frustuliae, and in general the 

 animalcules belonging to this series, object of the 

 present observations, have never appeared but in 

 cases where I could prove their external origin. I 

 never found these animalcules (except the Oscilla- 

 toriae often generated in infusions) but in river or 

 marsh waters, as well as all the more developed 



