308 BIOLOGY. [BOOK iv. 



The facts observed by F.-A. Pouchet lender moreover spon- 

 taneous generation much more intelligible. In effect, the birth 

 of infusoria, at least of the more complex infusoria, seems to be 

 preceded by the formation of a sort of living blastema, in the 

 heart of which the ovula originate, exactly as they originate by 

 spontaneous genesis in the blastemas of animals and plants. 



What radical difference is there between the formation of the 

 ovula in the proligerous pellicle of F.-A. Pouchet and the for- 

 mation of cellular elements under the microscope in saccharine 

 serum ? It is one of the adversaries of spontaneous generation, 

 M. Cl. Bernard, who affirms that he had observed this last fact 

 of veritable heterogenesis. 1 We must allow him to speak him- 

 self : " I have observed that in saccharine serum, under the 

 influence of a mild temperature, there are developed amyloidal 



productions perfectly analogous to the white globules 



In a drop of saccharine serum, completely transparent, and in 

 which the microscope reveals to us nothing, there are soon formed 

 leucocytes,. or globules of beer yeast." 



1 Cl. Bernard, Rapport sur les Progrte de la Physiologic, &c., pp. 210, 217. 



