Evolution of Evolution-Theory. 225 



main, but not the exclusive " factor in evolution, the 

 origin of variations being always assumed. To a cer- 

 tain extent, however, he believed in the inheritance of 

 acquired characters, and agreed with Buffon and La- 

 marck in recognizing the evolutionary importance of 

 the modifying influences of function and environment. 



After the publication of the Origin of Species, there 

 was a period of keen and often bitter criticism on the 

 one side, of exposition and corroboration on conflict of 

 the other. Spencer and Haeckel gave gener- Opinions, 

 alized expression to the more concrete arguments of 

 Darwin and Wallace, and Huxley formed the cutting 

 edge of the new Biology. None the less, the Darwinian 

 theory had a stern struggle for existence before its 

 survival was assured. For a time the question at issue 

 was one which is now almost out of date the question 

 between evolution and non-evolution, and during this 

 period the evolutionists allowed their differences of 

 opinion in regard to the factors to sink into relative 

 unimportance in their endeavour to present a united 

 front against the wide-spread opposition to the whole 

 idea. But as the intensity of criticism waned, the 

 various schools of evolutionists began to assert their 

 particular creeds. The majority, perhaps, were on the 

 whole Darwinian, sometimes tainted with "Lamarckian 

 heresy"; a minority reverted almost completely to Lam- 

 arck's position; others maintained the importance of 

 more or less unknown laws of growth; and a few 

 cautious spirits were convinced evolutionists, but ag- 

 nostic as to the factors. It may be said that within ten 

 years after the publication of the Origin of Species all 

 the diversity of opinion which confronts us to-day was 

 either clearly expressed or existed in rudiment. 



If we extend our survey on to "the coming of age" 

 of the Darwinian theory, and then take a cross-section 

 of opinion, we find serious opposition to the general 

 idea of organic evolution fast approaching a vanishing 

 point, but the tissue of evolution theories as hetero- 

 geneous as before. Three main schools may be distin- 

 guished. 



First, there is the predominantly Darwinian school, 



( M 523 ) P 



