CHAPTER XII 



The Law of Galton and the Laws of 



Mendel 



Heredity considered from a new point of view. — Galton's sta- 

 tistical researches : the law of ancestral heredity. — Mendel's 

 experiments. — The study of hybrids; the law of dominance 

 and the law of segregation of characters. — Instances of the 

 application of these laws. — Theoretical consequences of 

 the Mendelian discoveries. 



ALL the theories of heredity we have thus far 

 reviewed, endeavoured to solve the following 

 problem: by what physiological processus does an 

 organism become, in the course of its development, 

 similar to the organisms from which it is descended? 

 This problem, however, can be formulated in a differ- 

 ent way. We may set aside the phenomena arising 

 in the fertilised ovum and in the various tissues, and, 

 taking the resemblance which results from them as 

 granted, let our observations bear upon this resem- 

 blance, its various stages and its variations in the 

 course of several generations. This was the way in 

 which Galton and Mendel approached the subject. 

 The application of different methods, however, led 

 these two scientists to draw different conclusions. 



176 



