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one for the philosophic biologist, rather than the experimen- 
talist with his flasks, and decoctions, and air from the 
Pyrenees, and we do not know of one such who has been 
led to believe that Bacteria and Vibriones are produced 
casually from unorganized matter, though many believe in 
the possibility of the evolution of organic from inorganic 
matter. 
Appendix to the Principles of Biology. By Herbert 
Spencer. This is a reply to a criticism of Mr. Spencer’s 
philosophy which appeared in the North American Review. 
The reviewer charged Mr. Spencer with tacitly repudiating 
the belief in spontaneous generation, although endeavouring 
to prove the origin of all organic life by gradual development. 
To this Mr. Spencer replies that he does not believe in the 
“ spontaneous generation” commonly alleged, and referred 
to by the American reviewer. And he continues : — “ So 
little have I associated in thought this alleged ‘ spontaneous 
generation’ which I disbelieve, with the generation by evolu- 
tion which I do believe, that the repudiation of the one 
never occurred to me as liable to be taken for repudiation of 
the other. That creatures having quite specific structures 
are evolved in the course of a few hours, without antecedents 
calculated to determine their specific forms, is to me incre- 
dible. Not only the established truths of Biology, but the 
established truths of whence in general, negative the suppo- 
sition 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. If there 
can suddenly be imposed on simple protoplasm the organiza- 
tion which constitutes it a Paramcecium, 1 see no reason why 
animals of greater complexity, or indeed of any complexity, 
may not be constituted after the same manner. 
“ If, accepting these alleged cases of * spontaneous gene- 
ration,’ I had assumed, as your reviewer seems to do, that 
the evolution of organic life commenced in an analogous way ; 
then, indeed, I should have left myself open to a fatal criti- 
cism. This supposed ‘spontaneous generation’ habitually 
occurs in menstrua that contain either organic matter, or 
matter originally derived from organisms ; and such organic 
matter, proceeding in all known cases from organisms of a 
higher kind, implies the pre-existence of such higher or- 
ganisms. By what kind of logic, then, is it inferrible that 
organic life was initiated after a manner like that which In- 
fusoria are said to be now spontaneously generated ? Where, 
before life commenced, were the superior organisms from 
