146 THE THEOKY OF EVOLUTION 



generation was affirmed : the animals from gelatine 

 masses, the plants from masses of mucus. The finest 

 fluids penetrate these masses, make them soft ( = cellular) 

 and therefore suitable for life. Then, according to a 

 definite plan determined by the great Creator of all 

 things, there followed the creation of ever more and 

 more complicated forms. 



How did Lamarck arrive at such conclusions ? 



In the first place it appeared to him unnatural that 

 the successive organic worlds (creations), so different 

 from each other, should be destroyed by general cata- 

 strophes and then again replaced by a new creation in 

 altered forms. It appeared simpler to him to suggest 

 that the separate ' creations ' arose genetically from each 

 other. The variability of the organisms which is 

 certainly the premiss of all evolution he sought to show, 

 since he demonstrated to us thoroughly by examples 

 how organs can alter, though not that they do so in 

 point of fact. He was strengthened in his opinion 

 by the observation of the similarity of the organic 

 groups, which was most easily explained by a common 

 origin. Furthermore, it struck him how the organs of 

 the animals were so perfectly adapted to quite definite 

 needs, to a narrowly limited mode of existence. The 

 idea appeared to him to be closely associated that it 

 was just these needs which must be the cause that the 

 organs are precisely so constituted, often in a quite 

 wonderful and peculiar way. Lamarck then attempts 

 to make it comprehensible how the animals could 

 arrive at this purposeful constitution of their organs, 



