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 

 partiality 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 

 countrjmien, 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. LifC; by its proper forces, continually tends to increase the 

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

 parts, up to a limit which brings it about. 



II. 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 which this want gives rise to and maintains. 



III. The development of organs and their powers of action are 

 constantly in ratio to the employment of these organs. 



rV. Everything which has been acquired, impressed upon, or 

 changed in the organization of individuals during the course of their 

 life is preserved by generation and transmitted to new individuals 

 which have descended from those which have undergone these 

 changes. 



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

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

 "Lamarckian doctrine." 



A somewhat more specific statement of Lamarck's theory of 

 evolution may be simimed up in the following list 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 act directly in the case of 

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



2. "Needs, new physical wants or necessities induced by the 

 changed conditions of life. Lamarck believed that change of habits 



