66 INHERITANCE IN GUINEA-PIGS. 



VARIATIONS OF DARK COLOR (3) 



Factors of this group are responsible for browns and pink-eyed 

 sepias, as compared with blacks, in guinea-pigs; for browns and pink- 

 eyed sepias in mice, and for the new pink-eyed and red-eyed dilute 

 variations in rats. Where more than one factor of this group or of 

 group IB determines dilution, combination effects are produced. Thus 

 we have very pale sepias resulting from the combined effects of two 

 independent dilution factors 



jB. Determines a color of the black -sepia series wherever dark pigmentation develops, 

 including the eyes; has no influence where yellow pigmentation develops; domi- 

 nant over b, present in the wild species and in blacks, sepias, albinos with black 

 points, black-eyed yellows, etc. 



b. Determines a color of the brown series wherever dark pigmentation develops, including 

 the eyes; has no influence where yellow pigmentation develops; present in browns, 

 brown-eyed yellows, etc. (Castle, 1907a, 1908; Sollas, 1909; Detlefsen, 1914.) 



P. A condition for intense development of dark pigmentation in the fur and for eye colors 

 more intense than pink; not necessary for intense development of yellow; domi- 

 nant over p. 



p. Determines a low development of dark colors, i. e., below sepiag; has no influence where 

 yellow develops; determines pink eye color. (Castle, 1914a.) 



TABLE OF FACTOR COMBINATIONS. 



In determining the color which corresponds to a given array of factors 

 the groups of factors must be considered in the order given. Table 33 

 gives a list of the color varieties corresponding to the combinations of 

 Mendelian factors. At the top and left of the table are indicated, by 

 symbols, the factors present in each of the varieties named in the body 

 of the table. The color of spots produced by Sw and Sy are given 

 below. Only the varieties marked with an asterisk have not yet been 

 synthesized. These include the pink-eyed yellows and creams and a 

 kind of pink-eyed white which is expected to be indistinguishable from 

 an albino in appearance, though breeding wholly differently. The pink- 

 eyed brown series (bbpp) has not yet been produced and is not included. 

 Some of the varieties have names given by fanciers which have been 

 used in the literature. In this table, however, it seemed best to use a 

 consistent scheme of naming, indicating at once the color and pattern. 

 Agouti is used as the name for a pattern, the banding of hairs of pre- 

 dominantly a dark color with a yellow color. The names preceding 

 agouti give the two colors in each hair. The following table of syno- 

 nyms may be useful : 



Black-red agouti = golden agouti. 



Sepia-yellow agouti = yellow agouti. 



Sepia-cream agouti = silver agouti. 



Brown-red agouti = cinnamon. 



Brown-cream agouti = light cinnamon. 



Sepia = blue. 



Brown = chocolate. 



Brown eye = brown eye (Castle), ruby eye (Sollas). 



