DEFINITIONS 295 



Cross. Synonymous with hybrid. 



Cross-fertilization. The union of the egg cell of an individual with the 

 sperm cell of a different individual whether the organisms belong to the same 

 or different genotypes. 



Cross-over. A separation into different gametes, of determiners that 

 are usually coupled, and the. association of determiners in the same gamete 

 which are generally in different gametes. 



Detassel. To remove the tassel, as in maize. 



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. 



Determiner. Synonymous with gene or with factor as applied in genetics. 



Dominance. In Mendelian 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 condition between the two parents, but may 

 present new features not found in either parent. 



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" 

 character. (2) An individual possessing a dominant character in contrast to 

 those individuals which lack that character which are called "recessives." 



Ear. A large, dense or heavy spike or spikelike inflorescence as the ear of 

 maize. Popularly applied also to the spike-like panicle of such grasses 

 as wheat, barley, timothy and rye. 



Emasculation. The act of removing the anthers from a flower. 



Endosperm. The substance which surrounds the embryo in many seeds, 

 as the starchy part of a kernel of wheat or corn. 



Factor. An independently inheritable element of the genotype whose 

 presence makes possible a specific reaction or the development of a particular 

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

 determiner. 



Floret. A small flower, especially one of an inflorescence, as in grasses 

 and Compositse. 



Fi, F 2 , F?, etc. 1st, 2nd, and 3rd, etc. generations following a cross. 



Gamete. A reproductive cell containing x number of chromosomes. 



Gene. Synonymous with determiner or factor. 



Genotype. The fundamental hereditary constitution or sum of all 

 the genes of an organism. 



Glabrous. Smooth, especially without hairs. 



Glume. One of the two empty chaffy bracts at the base of each spikelet 

 in grasses. 



Grain. Cereal seeds in bulk. 



Group. In genetics a broad general term for a complex of other 

 categories and not for a complex of any particular category. 



Head. A dense, short cluster of sessile or nearly sessile flowers on a very 

 short axis or receptacle, as in red clover or sunflower. 



