THE TRANSMUTATION OF SPECIES. 243 



sophie Zoologique/ published in 1809, in two volumes 

 octavo ; and the fame of this rests in large part upon the 

 fact that it was here that he first laid down what may be 

 regarded as the earliest definite theory of evolution, as 

 applied to living beings. 



The only parts of Lamarck's theoretical views with 

 which we are specially concerned here, are those relating 

 to the nature of 'species,' and as to the way in which 

 species originated. Up to this time, naturalists in general 

 believed that though ' species ' might be capable of varia- 

 tion, such variations were only possible within certain 

 definite limits. On this view, a species might oscillate 

 backwards and forwards on both sides of a central line, 

 but it would sooner or later return to the position of 

 equilibrium represented by the type-form of the species. 

 This view was the one held by the illustrious Cuvier, 

 and by many naturalists long after the time of Lamarck. 

 Many, indeed, believed that ' species ' of animals and 

 plants were special creations, and as such necessarily in- 

 capable of transmutation. This, for example, was, as has 

 been seen, the view held by Edward Forbes. A few 

 observers (such as Dr Erasmus Darwin, Isid. Geoffroy 

 St Hilaire, and Goethe) had begun to doubt the stability 

 or permanence of species as early as the end of the 

 eighteenth century. Lamarck not only reached this belief 

 independently, but clearly formulated it, first in 1801, then 

 in the 'Philosophic Zoologique ' in 1809, and finally in 

 the introduction to the 'Animaux sans Vertebres' in 

 1815. 



Lamarck was led to his views as to the transmutability 

 of species by his study of varieties, the ever-recurring 



