CHAPTER SIX 
THE MOST IMPORTANT OF THE EXISTING BIOGENETIC 
THEORIES IN RELATION TO THE INHERITANCE OF 
ACQUIRED CHARACTERS, 
We believe it is unnecessary to discuss here in an 
exhaustive way the fact that the question of the admis- 
sibility or inadmissibility of the Lamarckian principle re- 
mains always distinct from, and entirely independent of 
the question of the evolutionary or epigenetic nature of 
development. Darwin in his evolutionary theory with 
preformistic germs,—a true theory of preformation,— 
accepts inheritance; Galton limits it to a few cases; Weis- 
mann excludes it unconditionally. Hertwig accepts it in 
his epigenetic theory, although he does not exclude some 
sort of preformistic germs; DeVries excludes it. Roux 
who was inclined at first to believe that this inheritance 
might exist in combination with the chemical develop- 
ment of the egg, a theory frankly evolutionary without 
preformistic germs, has finally regarded the two theories 
as irreconcilable. The only theories which appear es- 
pecially inclined toward the complete acceptance of the 
Lamarckian conception, are the epigenetic theories with- 
out preformistic germs, for example that of Spencer. 
We can now pass on to the rapid review of the 
principal biogenetic theories current today, with especial 
reference to their direct or indirect relation to the ques- 
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