THE RENASCENCE OF SCIENCE. 115 



To Lamarck, says Haeckel, " will always belong 

 the immortal glory of having for the first time worked 

 out the Theory of Descent as an independent sci- 

 entific theory of the first order, and as the philosophi- 

 cal foundation of the whole science of Biology." He 

 taught that in the beginnings of life only the very sim- 

 plest and lowest animals and plants came into exist- 

 ence; those of more complex structure developing 

 from these; man himself being descended from ape- 

 like mammals. For the Aristotelian mechanical figure 

 of life as a ladder, with its detached steps, he substituted 

 the more appropriate figure of a tree, as an inter- 

 related organism. He argued that the course of the 

 earth's development, and also of all life upon it, was 

 continuous, and not interrupted by violent revolu- 

 tions. In this he followed Buffon and Hutton. Buf- 

 fon, in his Theory of the Earth, argues that " in 

 order to understand what had taken place in the past, 

 or what will happen in the future, we have but to 

 observe what is going on in the present." This is 

 the keynote of modern geology. " Life," adds 

 Lamarck, " is a purely physical phenomenon. All 

 its phenomena depend on mechanical, physical, and 

 chemical causes which are inherent in the nature of 

 matter itself." He believed in a form of spontaneous 

 generation. Rejecting Buffon's theory of the direct 

 action of the surroundings as agents of. change in 

 living things, he sums up the causes of organic evo- 

 lution in the following propositions: 



i. Life tends by its inherent forces to increase 



