DEFINITIONS 1 



Acquired Character. A modification of bodily structure, function, 

 or habit which is impressed on the organism in the course of individual life. 



Aieurone. The outermost layer of the endosperm in cereals, when 

 it is rich in gluten. 



Allelomorph. One of a pair of contrasted characters which are alternative 

 to each other in Mendelian inheritance. Often used, but with doubtful 

 propriety, as a synonym for gene, factor, or determiner. 



Allelomorphism. A relation between two characters, such that the 

 determiners of both do not enter the same gamete but are separated into 

 sister gametes. 



Alternative Inheritance. A distribution of contrasting parental or 

 ancestral characters among offspring or descendants, such that the individ- 

 uals exhibit one or other of the characters in question, combinations or 

 blends of these characters being absent or exceptional. 



Anthesis. The period or act of flowering. 



Awn. A bristle-shaped elongated appendage or extension, to a glume, 

 akene, anther, etc. 



Barbed. Furnished with rigid points or short bristles, usually reflexed. 



Biotype. A group of individuals all of which have the same genotype. 



Bran. The coat of the caryopsis, consisting of pericarp and seed-coat 

 united. 



Caryopsis. A one-seeded dry fruit with the thin pericarp adherent to the 

 seed, as in most grasses. 



Centgener. Originally used by W. M. Hays, at the Minnesota Station, 

 to refer to a 100-plant plot in which each seed was planted a certain distance 

 from each other seed. 



Chaff. The floral parts of cereals, generally separated from the grain in 

 thrashing or winnowing. 



Chimera. An association of tissues of different parental origin and genetic 

 constitution in the same part of a plant. 



Chromosome hypothesis. The hypothesis advanced by Morgan in which 

 factors are arranged in the chromosomes. 



Class. In genetics a group that includes variates of similar magnitude. 



Clone. A group of individuals produced from a single original individual 

 by some process of asexual reproduction, such as division, budding, slipping, 

 grafting, parthenogenesis (when unaccompanied by a reduction of the 

 chromosomes), etc. 



Coefficient of Variability. A relative index of variation obtained by 

 expressing the standard deviation in percentage of the mean. 



Coupling. 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. 



1 Many of the genetic definitions are taken from Shull (1915), Babcock 

 and Clausen (1918) or others. Ball and Piper's (1916) papers on termi- 

 nology have been used for agronomical terms. 



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