xxxiv INTRODUCTION 



that in this way worms and infusorians come into being, 

 and that these organisms are at the same moment endowed 

 with a tendency to evolve, till they ultimately give rise to 

 all the higher races of animals. 



The second factor, which, according to Lamarck, operated 

 in the evolution of species, is that with which his name has 

 come to be so closely associated, namely, the inheritance of 

 acquired characters. This doctrine appears to have been 

 first enunciated in detail by Lamarck himself : it is natural 

 therefore, that he should dwell upon it at great length in 

 the present work. We must, however, recollect that he 

 looked upon it as subordinate to the main factor, just as 

 Darwin invoked it as subordinate to natural selection.i 

 His position was far indeed from that occupied, for instance, 

 by Herbert Spencer in 1852, when some evolutionists en- 

 deavoured to account for evolution with exclusive reference 

 to direct action of the environment. I shall deal with this 

 alleged factor in my next section : for the present I confine 

 myself to an account of Lamarck's views of the evolutionary 

 process. 



Lamarck held, then, that if it were not for the effects of 

 environmental influences, the innate tendency to develop 

 would be the exclusive factor in operation. We should 

 then see the linear series of animals to be a perfectly regular 

 and even progress in complexity of organisation from Monas 

 termo to man. Each animal born would presumably be 

 slightly more complex than its parent. If we could trace 

 the ancestry of man, we should find as we went backwards 

 that each individual was to an excessively small degree less 

 complex than its immediate neighbour, till finally we ended 

 with the infusorians. All existing animals are on the road 

 of development from Monas to man, and man's ancestors 

 include every existing species of animal. Not only had he 

 bird, reptile and fish ancestors, but also arachnid, insect, 



^ Professor Charles Martins in his introduction to the 1873 reprint of the Philosophie 

 Zoologique is so intent upon making out a ease for inheritance of acquired characters, 

 that he omits to make any mention whatever of Lamarck's primary factor. He has 

 thus helped to perpetuate a common error regarding Lamarck's views. 



