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THE AMERICAN NATURALIST [Vol. XLIX 



The defects consist, first, in the ambiguity of the word "stock," 

 because we may grow plants "from an original stock" of seeds, 

 quite as well as from cuttings, while a clone is derived from a 

 single individual; second, the statement that clones do not come 

 true from seed is incorrect, for a clone formed by cuttings, etc., 

 from a homozygous individual does "breed true," i. e., it pro- 

 duces seedling offspring of its own type. The word is now 

 being generally applied to animals as well as to plants. 



Coupling. ("Genetic coupling- is not defined in the dictionary.) Such 

 a relation between the genes of two unit-characters that they have a more or 

 less marked tendency to be included in the same gamete when the individual 

 is heterozygous for both of the genes in question. 



Cross-over. (Not given a genetic definition in the dictionary.) A sepa- 

 ration into different gametes, of determiners that are usually coupled, and 

 the association of determiners in the same gamete, which are generally allelo- 



Cryptomere. "A plant character which may exist in the germ-cells with- 

 out making its presence visible." 



Cryptomere. A factor or gene whose presence can not be inferred from 

 an inspection of the individual, but whose existence can be demonstrated by 

 means of suitable crosses. 



The chief defect in the dictionary definition is the restriction 

 of this term to plant characters. "Cryptomere" is a general 

 genetic term which may be applied as well to animals as to plants. 



Determiner. An element or condition in a germ-cell which is essential to 

 the development of a particular feature, quality or manner of reaction of the 



The word "determiner," as used in recent years, is not the 

 equivalent of "determinant 3," which latter is correctly defined 

 in the dictionary in terms of Weismann 's complicated hypothesis. 

 "Determiner," "factor" and "gene" are now quite generally 

 used interchangeably without implication as to their fundamental 

 nature, simply in the generic sense, as "that which determines." 

 Dominance. "I n the cross-bred offspring of parents with marked mu- 



descendants of one of these characteristics to the exclusion of the other." 



Dominance. In M< tuh.lian hybrids the capacity of a character which is 

 derived from only one of the two generating gametes to develop to an extent 

 nearly or quite equal to that exhibited by an individual which, has derived 

 the same character from both of the generating gametes. In the absence 

 of dominance the given character of the hybrid usually presents a "blend" 

 or intermediate conldition between the two parents, but may present new 

 features not found in either parent. 



There are several defects in the dictionary definition. In the 

 first place, the parents used in a given cross may not themselves 



