GLOSSARY 



In the following glossary of terms used in the text and the references no 

 attempt is made to furnish exact definitions. The purpose has been rather to 

 supply the secondary-school student with an adequate working idea of the 

 meaning of the terms as commonly employed, maintaining at the same time 

 scientific accuracy, without aiming to attain that exhaustive discrimination 

 which might be demanded by the highly specialized student. 



Accessory chromosome. That particular chromosome which, at least in certain 

 species, has its mate in the female but not in the male, and which is therefore 

 supposed to be associated with the determination of sex. 



Acquired character. Modification of hereditary characters due to environ- 

 ment or habits of life. 



Adaptation. The " fit " which is brought about between the environment and 

 the species. See Natural selection and Survival of the fittest. 



Advanced registry. A registry based on performance and not simply upon 

 pedigree. 



Ancestry. Those members of past generations that are related to any given 

 individual by descent. 



Average deviation. A mathematical expression measuring variability obtained 

 by averaging the deviation of all individuals from the mean of the race or 

 population. 



Breed. A definite variety or strain of animal bred to a special type. 



Breeding. The intelligent combining of known blood lines in either animal 

 or plant production. Specifically, also, the mating of animals. 



Biophere. A term used by Weismann (pronounced Visemdn) to denote the 

 smallest conceivable unit of living matter. 



Castration. The removal, by the knife, of the testicles of the male, thus pre- 

 venting reproduction. 



Character. Any trait, faculty, or physical feature of the individual or species 

 that can be identified and more or less accurately described. 



Characters, dominant. The more prominent of two mutually exclusive char- 

 acters, and which therefore characterize three fourths of the offspring of hybrid 

 parents. 



Characters, latent. Those racial characters that remain undeveloped and 

 therefore unnoticed in a given individual, but which may appear in his 

 descendants because belonging to the ancestry. 



Characters, recessive. The less conspicuous of two characters which are 

 mutually exclusive, and which therefore characterize but one fourth of the 

 offspring of hybrid parents. 



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