CHAPTER IX 



THE HETEROGENETIC ORIGIN OF BACTERIA AND THEIR ALLIES 



THE doctrine now to be dealt with, and for the estabUshment 

 of which I hope to bring forward very conclusive evidence, 

 is one which is as much opposed to common belief as that dealt 

 with in the last chapter. That Uke produces like — that the off- 

 spring of any plant or animal will in all cases develop into an 

 organism like its parent — is a belief as firmly rooted as that other 

 which is embodied in the phrase omne vivum ex vivo. 



We have found Herbert Spencer saying, " Not only the estab- 

 lished truths of Biology, but the established truths of Science in 

 general, negative the supposition that organisms, having structures 

 definite enough to identify them as belonging to known genera and 

 species, can be produced in the absence of germs derived from ante- 

 cedent organisms of the same genera and species." ' Similarly, Pasteur 

 was no less positive in his opposition to Heterogenesis. " For 

 nearly twenty years," he said, " I have pursued without finding it, 

 a proof of life existing without an anterior and similar life. The 

 consequence of such a discovery would be incalculable ; natural 

 science in general, and medicine and philosophy in particular, would 

 receive therefrom an impulse which cannot be foreseen." = 



If I am equally positive, in spite of the dicta of these authorities, 

 that Heterogenesis is a reality, I can only say that this view has 

 been forced upon me after years of work commenced more than 

 thirty years ago, and now again resumed during the last six years. 



In Archebiosis we are concerned with the actual origin of living 

 matter, while in Heterogenesis we have to do with the transforma- 

 tion of already existing living matter, and a consequent new birth 

 of alien living things — as when the substance of an encysted 

 Euglena or of an encysted Ciliate becomes transformed into a 

 brood of Monads, Amoebae, or Peranemata ; when similar 



' " Biology," I, Append, D, p. i68. No italics in original. 



' " The Life of Pasteur," by Vallery-Radot, 1902, Vol, II, p. 41. 



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