Biometry. — The branch of science dealing with the 

 statistical investigation of organic differences. 



Bud Mutation. — A mutation occurring in the very ear- 

 ly history of a bud such that a branch is produced which 

 differs genetically from the remainder of the plant. 



Chimera. — A mixture of tissues of different genetic 

 constitution in the same part of a plant. 



Chromomeres. — The chromatin granules, which are 

 sometimes arranged like the beads on a necklace. 



Chromosomes. — Term applied to certain minute bodies 

 in the nucleus of the animal and vegetable cell, which appear 

 at definite periods in the division of the cell, and are con- 

 stant in number for each species of animal or plant. 



Clone. — A group of individuals produced from a single 

 original individual by some process of asexual reproduction 

 such as division, budding, slipping, grafting, parthenogene- 

 sis (when unaccompanied by a reduction of the chromo- 

 somes), etc. 



Crossing-over. — Exchange of chromatin material be- 

 tween homologous chromosomes. 



Cytology.— The branch of biology which treats of cells, 

 especially of their internal structure. 



Cytoplasm. — That portion of the protoplasm of the cell 

 outside the nucleus. 



Diploid. — The number of chromosomes normally 

 found in the somatic cells of a species; twice the gametic 

 or haploid number. 



Endosperm. — The substance stored in a seed adjacent 

 to the embryo for its early nourishment. 



Fi, a symbol introduced by Mr. Bateson, as an abbre- 

 viation for the first hybrid generation. 



Fo, a symbol for the se^nd hybrid generation. 



F3, a symbol for the third hybrid generation. 



Factor.— An independently inheritable element of the 

 genotype by the presence of which some particular charact- 

 er in the organism is made possible; gene; determiner. 



Fertilization. — The union of male and female sex cells. 



Fluctuations (Fluctuating Variations.)— The slight dif- 

 ferences normally found in organisms and attributed either 

 to environmental influences or to recombinations of genetic 

 factors. 



Gene. — See factor. 



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