THE WORMS 



71 



or spores can not pass from the air without into the steril- 

 ized liquid, no living animals will ever appear in it. It is 

 now known that flesh will not decay or liquids ferment 

 except through the presence of living animals or plants. 



FIG. 38. The multiplication of Amffiba by simple fission. 



To sum up, we may say that we know of no instance of the 

 spontaneous generation of organisms, and that all the ani- 

 mals whose life history we know are produced from other 

 animals of the same kind. " Omne vivum ex vivo" All life 

 from life. 



