LAMARCK'S FOUR LAWS 221 



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and like the German transcendentalists, Lamarck makes 

 man the goal of evolution (p. 116). He makes it quite clear 

 that his Echelle is a functional one, for he links Vertebrates 

 to molluscs even while expressly admitting that they are 

 not connected by any structural intermediates (p. 123). He 

 does not fall into the error of the transcendentalists and 

 assume that Vertebrates and Invertebrates alike are formed 

 upon one common plan of structure. 



The progression of organisation shown by the animal 

 kingdom has not been altogether regular and uninterrupted : 

 " The progression in complexity of organisation shows here 

 and there, in the general animal series, anomalies induced 

 by the influence of environment and by the influence of the 

 habits contracted " (Phil, zool, i., p. 145). 



There are thus really two causes at work to produce the 

 variety of organisation as it appears to us, one which tends 

 to produce a regular increase in complexity, and one which 

 disturbs and diversifies this regular advance. 



The first cause Lamarck calls the vital power (pouvoir de 

 la vie} ; the other may be called the influence of circumstance 

 (An/in, s. Vert., p. 134). To the latter cause are due the 

 lacuna, the blind alleys, and the complications which the 

 otherwise simple scale of perfection shows. 



To explain both these aspects of evolution Lamarck 

 propounded in his volume of 1816 four laws, which read as 

 follows : 



" First Laiv. Life, by its own forces, tends continually to 

 increase the volume of every body possessing it, and to 

 extend the dimensions of its parts, up to a limit which it 

 brings about itself. 



" Second Law. The production of a new organ in an 

 animal body results from the arisal and continuance of a 

 new need, and from the new movement which this need 

 brings into being and sustains. 



" Third Laiu. The degree of development of organs and 

 their force of action are always proportionate to the use made 

 of these organs. 



" Fourth Laiv. All that has been acquired, imprinted or 

 changed jn the organisation of the individual during the 

 course of its life is preserved by generation and transmitted 



