An analysis of Wilhelm Johannsen's genetical genotype “term” 1909-26

An investigation of the genetical terms coined by Wilhelm Johannsen in 1909 showed the term GENOTYPE to have undergone a very complicated development in the period from 1909 to 1926, when it was defined for the third time in the 1926 edition of “Elemente der exakten Erblichkeitslehre”. The term was originally used to describe the abstract hereditary effect upon the individual, but was changed in 1913 to cover the concrete cause itself, the “sum total of genes“, this latter definition being generally accepted. Finally the term underwent a change in 1926 to cover a new abstraction, namely the constitution of the organism as the cause of development. In order to obtain a more concise correspondence between the term itself and its meaning, the present author suggests that the term GENOTYPE should be used to describe the concrete cause, the “characteristical genes” and proposes a new term, the HERITYPE, to describe the 1909 genotype abstraction, namely the “hereditary part of the phenotype”.