HISTORICAL ACCOUNT OF EVOLUTION THEORY 



19 



from Botany to Zoology, without gaining the greatest admiration for 

 his genius. No one has been more misunderstood, or judged with more 

 partiaHty by over or under praise. The stigma placed upon his writ- 

 ings by Cuvier, who greeted every fresh edition of his words as a 

 'nouvelle folic,' and the disdainful illusions to him by Charles Darwin 

 (the only writer of whom Darwin ever spoke in this tone) long placed 

 him in the light of a purely extravagant, speculative thinker. Yet, 

 as a fresh instance of the certainty with which men of science finally 

 obtain recognition, it is gratifying to note the admiration which has 

 been accorded to him in Germany by Haeckel and others, by his 

 countrymen, and by a large school of American and English writers 

 of the present day; to note, further, that his theory was finally taken 

 up and defended by Charles Darwin himself, and that it forms the 

 very heart of the system of Herbert Spencer." 



Lamarck's main theory of evolution was expressed by him in the 

 form of his four "laws": 



I. " Life, by its prop er forces^ontinually tends to increase the I 

 volume of every body which possesses it, and to increase the size of ifs ' 



parts, up to a lirnit whicE~bfmp it about. 



^ IT. "The production of a new organ in the animal body results' 

 from the supervention of a new want which continues to make itself __ 



felt , and a new movement whichJ.his.waaLgLY£s rise to and maintains. 



III. "The development of organs and their powers of_action are ! ^j 

 constanihLJn ratio to the cn:ii)Iii\nicnt of these organs. _ 



d upon 



IV. "Everything which has been acquired, im p^'p ssect upon, o r 

 changed in the organization of indivi duals during the ron rcp r-.f tVi^^jr 

 IH e is pt s^r ved by ge neration and transmitted to new individuals 

 wmch have descende 



lave underp^one these 

 tiiajigegJI 



It is about the last " law " that the controversy rages, for it upholds 

 the idea that acquired characters are hiJierited, now known as the 

 "Lamarckian doctrine." 



A somewhat more specific statement of Lamarck's theory of 

 evolution may be summed up in the following hst of factors which he 

 considered as playing an essential role in evolution. 



1. " Favorable circumstances attending changes of environment. 

 soil, food, temperature, etc., supposed to arf dirprtjy in the case of 

 plants, indirectly in the case of animals and man. " 



2. "Ne eds, new p h ysical wants or necessities in duced by the 

 changeoc^nditions of life. Lamarck believed that change of habits 



