THE BEGINNINGS OF LIFE. 261 



J. Miiller, Dujardin, and Burdach, who were all more or 

 less in favour of the doctrines of heterogeny. These 

 views received their fullest and most complete expo- 

 sition, however, from the last whom we have men- 

 tioned. In his well-known work, Burdach gave a some- 

 what detailed account of his views on that primordial 

 mode of generation to which he first attached the name 

 c generatio heterogenia.' But like those of his pre- 

 decessors and fellow-countrymen, Bremser and Tie- 

 demann,, his views were of a retrograde description, 

 when compared with those of Lamarck. He no longer 

 limited the possibility of such a mode of origin to the 

 lowest members of the animal and the vegetable king- 

 doms, but also contended that certain worms, insects, 

 Crustacea, and even fish might in this way appear upon 

 the scene without ordinary parentage. 



After him, however, came Pineau in 1845, who de- 

 clared that he had actually watched, step by step, the 

 heterogenetic origin and development, of two ciliated 

 infusoria Monas lens and a Vorthella and also of a 

 microscopic fungus Penicillium glaucum. This was the 

 first announcement of a kind of evidence altogether 

 new based upon actual observation rather than upon 

 experimental inference. 



Advocates of the opposite or panspermic doctrine, 

 however, were abundant enough also during the first 

 half of the present century : amongst the most distin- 

 guished of these must figure the names of P. Gervais, 

 Schwann, Schultze, and Ehrenberg. The latter, in his 



