ARISTOTLE ON THE ORIGIN OF LIFE. ']'] 



there alone, during a period of more than two thousand 

 years, in the region of empirico-philosophical knowledge of 

 nature, and especially in his knowledge of organic nature, is 

 proved to us by the precious remains of his but partially 

 surviving works. In them many traces are found of a 

 theory of natural development. Aristotle assumes, as a 

 matter of certainty, that spontaneous generation was the 

 natural manner in which the lower organic creatures came 

 into existence. He describes animals and plants originating 

 from matter itself, through its own original force ; as, for 

 example, moths from wool, fleas from putrid dung, wood-lice 

 from damp wood, etc. But as the distinction of organic 

 species, which Linnseus only arrived at two thousand years 

 later, was unknown to him, he could form no ideas about 

 their genealogical relations. 



The fundamental notion of the theory of development, 

 that the different species of animals and plants have been 

 developed from a common primary species by transformation, 

 could of course only be clearly asserted after the kinds oi 

 species themselves had become better known, and after the 

 extinct species had been carefully examined and compared 

 with the living ones. This was not done until the end 

 of the last and the beginning of the present century. 

 It was not until the year 1801 that the great Lamarck 

 expressed the theory of development, which he, in 1809, 

 further elaborated in his classical " Philosophic Zoologique." 

 While Lamarck and his countryman, Geoffroy St. Hilaire, in 

 France, opposed Cuvier's views, and maintained a natural 

 development of organic species by transformation and 

 descent, Goethe and Oken at the same time pursued the 

 same course in Germany, and helped to establish the theory 



