514 EVOLUTION, HEREDITY, EUGENICS 



2. The production of the new organ or part in the animal body- 



results from the supervention of a new need or want which 

 continues to be felt and of a new movement which this need 

 initiates and causes to continue. 



3. The development of organs and their force or power of action 



are always in direct relation to the employment of those 

 organs. (Law of use.) 



4. All that has been acquired, impressed upon or altered in the 



organization of individuals during the course of their life is 

 conserved by the generation and transmitted to new indi- 

 viduals which have descended from those which have sur- 

 vived these changes. 



Following the death of Lamarck in 1829, the theory of Evolution 

 was forgotten for a time and ceased to impress the scientific world. 

 Erasmus Darwin's views were not revived until the time of his 

 grandson, Charles Darwin. 



Cuvier (1769-1832), the founder of Modern Paleontology, was a 

 keen student of anatomy, beginning with Invertebrates. He is 

 termed the founder of Comparative Anatomy, as he established a 

 system of classification based on the comparative' anatomy of 

 internal organization instead of the superficial external characteris- 

 tics employed by his predecessors. He defended his erroneous 

 " cataclysm theory," that periodically a great revolution destroyed 

 all life on the earth and that a new world of unchangeable species 

 arose. This theory was later, in 1832, shown to be false by Lyell, 

 in his " Principles of Geology." 



Charles Darwin (1809-18 8 2). — According to Charles Dar.win, in 

 1858, chance variations afford the opportunity for the factor of 

 natural selection to pick out those best adapted to survive in the 

 tremendous struggle for existence and the propagation of species. 



Darwin took variations for granted. His long observations, 

 together with the suggestive work of Malthus on Population, con- 

 vinced him of the tendency towards over-production in plants and 

 animals. This, he noted, led to a struggle for existence. He pointed 

 out the fact that struggle for existence might be between fellows, 

 when stags fight stags in the clearing, or between foes as in the case 

 of the mongoose and the snake; or finally it might be a struggle with 

 fate, as in the case of " two canine animals which in time of dearth 

 struggle with each other which shall get food and live." 



