EVOLUTION 1 6 1 



of nature. 11 It was this observation of the gradual perfecting 

 of living organisms from the simplest to the most com- 

 plicated that inspired Lamarck with the idea of evolution 

 and transformation. " How," he says, "can we help searching 

 for the cause of such wonderful results? Are we not com- 

 pelled to admit that nature has produced successively bodies 

 endowed with life, proceeding from the simplest to the most 

 complex P 11 



The various products of nature have been divided into 

 classes, genera, and species, simply to facilitate their study. 

 Modern research tends to show that there is no definite line of 

 demarcation even between the animal, vegetable, and mineral 

 kingdoms. All our classification is artificial, and the passage 

 from one division to another is gradual and insensible. 

 Lamarck expresses this idea very clearly : " We must remember 

 that classes, orders, and families, and all such nomenclature, are 

 methods of our own invention. In nature there are no such 

 things as classes or orders or families, but only individuals. 

 As we become better acquainted with the productions of 

 nature, and as the number of specimens in our collections in- 

 creases, we see the intervals between the classes gradually fill 

 up, and the lines of separation become effaced." 



Lamarck also raises his voice against the supposed 

 immutability of species. "Species have only a relative 

 constancy, depending on the circumstances of the individuals. 

 The individuals of a given species perpetuate themselves with- 

 out variation only so long as there is no variation in the 

 circumstances which influence their existence. Numberless 

 facts prove that when an individual of a given species changes 

 its locality, it is subjected to a number of influences which 

 little by little alter, not only the consistency and proportions 

 of its parts, but also its form, its faculty, and even its organiza- 

 tion ; so that in time every part will participate in the 

 mutations which it has undergone. 11 



Lamarck also clearly affirms the fact of spontaneous 



(feneration. " I hope to prove," he says, " that nature possesses 



means and faculties for the production of all the forms which 



we so much admire. Rudimentary animals and plants have 



1 1 



