53 THE AMERICAN NATURALIST [VOL. XLIX 



essentially the same definition should not have been given at 

 both places. 



Allelomorph. "In Mendelian inheritance a pair, of contrasted characters 

 which become segregated in the formation of reproductive cells." 



Allelomorph. One 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. (6) 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 

 sister gametes. 



Alternative inheritance. "The transmission to alternating generations 

 of descendants of the characteristics of either parent, as that of the father 

 to the odd, and of the mother to the even generations." 



Alternative inheritance. A distribution of contrasting parental or an- 

 cestral characters among offspring or descendants, such that the individuals 

 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 of 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 general 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. 



Clon. "A plant-group the members of which have been grown from an 

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



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. 



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 Eeport of the third International Conference of Genetics, p. 98. 



