55 THE AMERICAN NATURALIST [VOL. XLIX 



be homozygous, in which case some of their offspring will resemble 

 one parent and some the other; in such a case, according to the 

 dictionary, both of the contrasted characters would exhibit domi- 

 nance. The phrase "or its descendants " would make it pos- 

 sible, in any case, to include both recessives and dominants, since 

 among the descendants of such cross-bred individuals there will 

 also be recessive individuals which ' ' exhibit one of the character- 

 istics to the exclusion of the other." 



Dominant, " (1) A marked parental character exhibited by a cross-bred 

 organism and its descendants. (2) The parent, cross-bred organism, or 

 descendant exhibiting such character. Parental characters latent in a cross- 

 bred organism, but actively evidenced by its descendants, are called reces- 

 sives, as are the descendants which exhibit them." 



Dominant. (1) A character which exhibits dominance, i. e., that one of 

 two contrasted parental characters which appears in the individuals of the 

 first hybrid generation to the exclusion of the alternative, "recessive," char- 

 acter. (#) An individual possessing a dominant character, in contrast to 

 those individuals which lack that character, which are called ' ' recessives. ' ' 



An "extracted dominant," as denned in the dictionary, is not 

 distinguishable from the pure homozygous dominant used in the 

 cross from which the dominant in question was ' ' extracted, " as 

 no mention is made of the essential historical fact' that it is of 

 hybrid origin and that its parent or other known ancestor did not 

 breed true to the same dominant character. 



Factors. ' ' Latent physiological units which upon crossing give rise to 

 the new characters found in the hybrid." 



Factor. An independently inheritable element of the genotype whose 

 presence makes possible any specific reaction or the development of any par- 

 ticular unit-character of the organism which possesses that genotype; a gene 

 or determiner. 



The limitation of the term "factor" to those cases in which new 

 characters appear in hybrids, is not in accord with present usage. 

 All the various characters of organisms are to an important degree 

 dependent upon the existence of genotypic factors, regardless of 

 the behavior of these organisms in crosses. 



Gen. "A minute hypothetical particle supposed to be the bearer of he- 

 reditary qualities. ' ' 



Gene. An element of the genotype; a genetic factor; a determiner. 



The treatment of this word in the dictionary is particularly 

 mischievous. When I introduced the word "gene" to English- 

 reading students, I said: 3 "This word is proposed by Dr. 

 Johannsen ... to denote an internal something or condition 

 upon whose presence an elementary morphological or physio- 

 logical characteristic depends. The word 'gene' has the advan- 



3 AM. NAT., 43, p. 414, 1909. 



