SPONTANEOUS GENERATION. 



12. SPONTANEOUS GENERATION. 



Spontaneous or Equivocal generation is the term applied 

 to the alleged production of living beings without the pre- 

 existence of germs of any kind, and therefore without the 

 pre-existence of parent organisms. The question is one which 

 has been long and closely disputed, and is far from being 

 settled ; so that it will be sufficient to indicate the facts upon 

 which the theory rests. 



If an animal or vegetable substance be soaked in hot or 

 cold water, so as to make an organic infusion, and if this in- 

 fusion be exposed for a sufficient length of time to the air, 

 the following series of changes is usually observed. 



1. At the end of a longer or shorter time, there forms upon 

 the surface of the infusion a thin scum, or pellicle, which, 

 when examined microscopically, is found to consist of an in- 

 calculable number of extremely minute molecules. 



2. In the next stage these molecules appear, many of them, 

 to have melted together in twos and threes to form short fila- 

 ments, called 'bacteria,' which become longer by the apposi- 

 tion of fresh molecules at their extremities, or by uniting 

 with one another, when they are termed ' vibriones.' Both 

 the bacteria and the vibrios now exhibit a vibratile or serpen- 

 tine movement through the surrounding fluid. 



3. After a varying period, the bacteria and vibrios become 

 motionless, and disintegrate so as to produce again a finely 

 molecular pellicle. 



4. Little spherical bodies now appear, each of which is 

 provided with a vibratile cilmm with which it moves actively 

 through the infusion. (Monas lens.) 



5. Varied forms of ciliated Infusoria some which possess 

 a mouth and are otherwise highly organised make their 

 appearance in the fluid. 



The above is the general sequence of the phenomena which 

 have been observed, and the following are the two theories 

 which have been advanced to account for them. 



a. By the advocates of spontaneous generation, or 'Hetero- 

 geny,' it is affirmed that the Infusoria, which finally appear in 

 the infusion, are produced spontaneously out of the molecular 

 pellicle, the molecules of which are also of spontaneous origin, 

 and are not derived from any pre-existing germs. 



b. By the ' panspermists,' or the opponents of spontaneous 

 generation, it is alleged, on the other hand, that the produc- 

 tion of Bacteria, Vibrios, Monads, and Infusoria, in organic 

 infusions is due simplv to the fact that the atmosphere, 

 and probably the fluid itself, is charged with innumerable 



VOL. i. D 



