GROWTH OF IDEAS 283 



preference of more risky and more subtle hypotheses 

 instead of plain conclusions from obvious facts. 

 Finally, there is the theological opposition to 

 Haeckel that increased with every book in which 

 he put his ideas before the general public and 

 helped them (in their boundless professional 

 wisdom) to realise the danger of the situation. 



The year 1877 was a critical one in this respect. 

 In the middle of his struggles Haeckel retained 

 all the simplicity of his nature. He saw that the 

 idea of evolution was triumphing over all obstacles 

 and rapidly securing the allegiance of the best 

 men of the time. On the 18th of September, 1877, 

 he spoke of this with unrestrained * delight at 

 the scientific congress at Munich. He described 

 the theory of evolution as "the most important 

 advance that has been made in pure and applied 

 science." Then Eudolf Virchow delivered a 

 speech at the same congress. 



There is no doubt whatever that in the period 

 since Virchow had indicated a neutral field in 

 1863, in which science might effect " its com- 

 promise," Haeckel had boldly invaded that 

 province. In the previous year he had published 

 a little work called The Perigenesis of the Plas- 

 tidules, or the Generation of Waves in Vital 

 Particles. It was delivered in lecture-form at the 

 medical-scientific congress at Jena in November, 

 1875, and then printed on the occasion of Seebeck's 

 jubilee, May 9, 1876. Possibly it is the least 

 known of all Haeckel's works, though in my 

 opinion it is one of the most valuable in regard 



