COLOR 51 



the time absent from the gamete (or if not absent, then represented by 

 an alternative condition) . This is simply another way of stating the funda- 

 mental Mendelian principle that heterozygotes do not breed true, but 

 form at least two different kinds of reproductive cells. 



The breeder has to deal always with individuals, and only indirectly 

 with gametes. Therefore zygotic formulae are to him quite as important 

 as gametic formulae. Accordingly in what follows we shall endeavor to 

 give the zygotic formula of each variety described. Its breeding capac- 

 ity may quickly be inferred from an inspection of its zygotic formula. Each 

 factor which is double in the zygote will be represented in every gamete 

 formed, each factor which is single in the zygote will be present in only 

 half the gametes formed, or will be represented by the alternative (reces- 

 sive) condition expressed in the zygotic formula by a symbol in paren- 

 thesis. 



The zygotic formula of a gray rabbit which breeds true (an ordinary 

 wild one, for example) is B 2 Br 2 E 2 A 2 C 2 I 2 U 2 Y 2 , and the interrelations of 

 these factors, as at present understood, may be expressed in a diagram. 





Other gray rabbits are single (or heterozygous) as regards one or more 

 of the factors enumerated in this formula, though none of them lacks 

 altogether any one of these 8 factors. When a factor drops out altogether 

 a new color variety is produced. New color varieties have undoubtedly 

 originated in this way in the past, and are still doing so at the present 

 time. A maturation division in which the two components of a double 

 factor should fail to separate (as they do normally) might be the starting- 

 point of a new color variety, since it would result in the production of a 

 gamete which lacked a particular factor. Abnormal maturation divi- 

 sions, therefore, may be the immediate cause of color variations. 



COLOR VARIETIES OF THE RABBIT. 



It is impossible to make a scientific classification of the color varieties 

 of the rabbit without discarding or modifying some of the names now 

 in use; for many of these names are either without significance or are 

 misleading. From a perusal of the literature of the rabbit-fancy, we are 

 unable to decide what certain named varieties are, and it is more than 

 likely that we are not acquainted at first-hand with many varieties known 

 to the fancy in Europe. All such cases must necessarily be omitted, for 

 the present, from our classification. 



For convenience we may recognize 4 general color types, viz, (i) gray, 

 (2) black, (3) yellow, and (4) white. Each of the pigmented varieties 



