54 HEREDITARY CHARACTERS 



number are equally convinced that acquired characters may 

 be and are transmitted. The theories supported by these 

 two different sections of biologists involve the whole question 

 of evolution, that is, the question as to how complicated 

 organisms have been produced in the course of long ages 

 from pre-existing and simpler forms. Before considering 

 the evidence for and against the transmission of acquired 

 characters, it is necessary, therefore, to deal briefly with the 

 existing theories that bear upon this point. There are many 

 subdivisions and modifications of the more generally known 

 theories, and it will only be possible to deal here with the 

 most important and most generally known in their simplest 

 form. 



The theory of Lamarck was generally accepted by bio- 

 logists before the time of Darwin and Wallace, and is still, 

 in a modified form, accepted by a great many. . Lamarck 

 assumed that characters due to environment that were 

 acquired by parents were by them transmitted to their 

 offspring. He would explain that the antlers of a stag 

 were developed somewhat in the following manner. The 

 bucks fought with each other for the does, and they fought 

 by butting at each other's heads. This produced callosities 

 on the forehead. These callosities were transmitted to the 

 male offspring, which went on butting and made the callosity 

 larger. This went on for many generations, until the antlers 

 reached their present size and form. Again, the deer generally 

 developed their speed also through the transmission of ac- 

 quired characters. The individual deer, being chased by 

 animals of prey, acquired considerable speed in its efforts 

 to escape. This speed was transmitted to its offspring. The 

 offspring were also chased by beasts of prey, and developed 

 speed in addition to what they had inherited from their 

 parents, and so on from generation to generation. 



The theory that evolution is due to the action of natural 

 selection upon inborn variations was published by Darwin 

 and Wallace simultaneously. Darwin, while admitting the 

 possibility of the transmission of acquired characters some- 



