No. 577] NOTES AND LITERATURE 



53 



essentially the same definition should not have been given at 

 both places. 



n Mendelian inheritance a pair of contrasted characters 

 } segregated in the formation of reproductive cells." 



e of a pair of contrasted characters which are alternative 

 to each other in Mendelian inheritance. Often used with doubtful pro- 

 priety as a synonym for gene, factor or determiner. 



The defects in the dictionary definition in this case are two: 

 (a) The definition is plural, while " allelomorph " is singular; 

 the "allelomorph" is not a pair of characters, but a single char- 

 acter. (&) No segregation of allelomorphs takes place in the 

 formation of asexual reproductive cells. 



Allelomorphism. "The presence of allelomorphic pairs of characters." 

 Allelomorphism. A relation between two characters, such that the de- 

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



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

 these characters being absent or exceptional. 



Biotype. ' < In Mendelian inheritance a race or strain that breeds true or 

 almost true; a term introduced by Johannsen." 



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



The word "biotype" was introduced into English by Dr. 

 Johannsen 2 in 1906 with the definition "one single 'sort' of 

 organisms." It is a term of irenenil applicability and not limited, 

 to Mendelian races, as stated in the New Standard Dictionary. 

 Although homozygous biotypes generally do breed true, this is not 

 an essential feature and therefore should not be included in the 

 definition. Ever-sporting varieties are now well known which do 

 not breed true, but which, so far as present evidence goes, do 

 constitute single homozygous biotypes. Heterozygous biotypes 

 generally do not breed true. 



original stock, but which do not come true from seed." 



grafting, parthenogenesis (when unaccompanied by a reduction of the 



There are several defects in the dictionary definition of this 

 word, even if restricted to a plant-group in accord with the 

 original meaning given to it by Webber, who introduced the word. 



2 Report of the third International Conference of Genetics, p. 98. 



