Fj, Fg, F3. — First, second and third generations, respectively, 

 following a cross. 



Double Fj. — A cross between two F^s such that the 

 hybrid has all four grand-parents different. 



F2 Ratios. — The expected proportion of other types to the 

 bottom recessive in F^ is found by calculating 4° where n is 

 number of factors involved. In a monofactorial cross 4° = 4 

 and the expected ratio is 3:1, with 2 factors 4° = 16 and the 

 ratio is 15:1, with three factors 4° = 64 and the ratio is 

 63:1, etc. 



Factor. — A unit occupying a fixed chromosomal locus and 

 governing, or affecting, the transmission and development of a 

 heritable character; gene. 



Factor-pair. — See Allelomorph. 



Fallopian Tube. — The first portion of the MuUerian duct 

 in mammals which conveys ova from the peritoneal cavity to 

 the uterus. The upper portion of the oviduct. 



Familial. — In the clinical sense : transmitted in families but 

 with no unbroken continuity from generation to generation. 



Family. — (Animal breeding.) A group of individuals within 

 a breed, all of which have pedigrees which trace directly in 

 the female line to a common ancestress called the foundress 

 of the family. At times used in reference to the male line of 

 descent, in which case it is used interchangeably with line 

 of breeding (Winters). 



Fancier's Dominance. — Dominance built up by selection 

 (especially in such characters as coat colour and bizarre ap- 

 pearances), such dominance breaks down if crossed and back- 

 crossed with a variety which has not undergone such selection. 

 cf. Conditioned Dominance. 



Farina. — An obsolete synonym for pollen. 



Fatuoids. — A group of three types of oat mutants which 

 resemble Avena fatua. 



Fecundation. — Fertilization. 



Female Pronucleus. — The nucleus of a female gamete. 



