THE 



AMERICAN NATURALIST 



Vol. XLV March, 1911 No. 531 



THE GENOTYPE CONCEPTION OF HEREDITY 1 

 PROFESSOR W. JOIIANNSEN 

 University of Copenhagen 



Biology has evidently borrowed the terms "heredity" 

 and "inheritance" from every-day language, in which the 

 meaning of these words is the "transmission" of money 

 or things, rights or duties — or even ideas and knowledge 

 — from one person to another or to some others: the 

 "heirs" or "inheritors." 



The transmission of properties — these may be things 

 owned or peculiar qualities — from parents to their 

 children, or from more or less remote ancestors to their 

 descendants, has been regarded as the essential point in 

 the discussion of heredity, in biology as in jurisprudence. 

 Here we have nothing to do with the latter ; as to biology, 

 the students of this science have again and again tried to 

 conceive or "explain" the presumed transmission of 

 general or peculiar characters and qualities "inherited" 

 from parents or more remote ancestors. The view of 

 natural inheritance as realized by an act of transmission, 

 viz., the transmission of the parent's (or ancestor's) 

 personal qualities to the progeny, is the most naive and 

 oldest concex>tion of heredity. We find it clearly devel- 

 oped by Hippocrates, who suggested that the different 

 parts of the body may produce substances which join in 

 the sexual organs, where reproductive matter is formed. 



1 Address before the American Society of Naturalists, December, 1910. 

 129 



