NOTES AND LITERATURE 



RECENT EXPERIMENTS OX THE INHERITANCE OF 

 COAT COLORS IX MICE 

 The domesticated varieties of rodents, rabbits, guinea-pigs, 

 rats and mice, have furnished exceptionally favorable material 

 for analyzing the facts of Mendelian inheritance. The simple 

 formulae that at first sufficed to explain the results have become 

 more complex as the work has progressed until, at present, the 

 situation has become not a little intricate owing to the different 

 interpretations that the facts have received. This complication 

 is. however, paralleled by progress in the study of plants, fowls, 

 pigeons, sheep, swine, beetles, moths, snails, etc. Despite the 

 elaboration that Mendel's originally simple law has undergone, 

 it is significant how little there is in later discoveries that is 

 believed to be incompatible in principle with this law, which may 

 seem to vindicate itself in every direction where new facts come 

 to light. This is nowhere better illustrated than in the latest 

 facts and newest theories relating to inheritance of color in mice. 



The earlier work of Allen, Darbishire, Davenport and Cuenot 

 has given the relative order of dominance of the colors. These 

 stand yellow (Y), gray (G), black (B), chocolate (Ch) and 

 white (W). Each color is dominant to all that follow it in the 

 order given and recessive to all that precede. Cuenot 's results 

 with white mice— albinos— showed that albinos stand in a class 

 by themselves. White mice may carry latent 1 the factor for 

 producing any color, although so long as white mice are mated, 

 they produce only white. Cuenot 's suggestion has been widely 

 adopted, namely, that two factors are essential to produce any 

 color; one of these is common to all colors and is called the color 

 producer (C), the other is specific for each special color (Y, G, 

 B or Ch). When C is absent, no color can arise, although the 

 other factor, the determinant, may be present ; hence white mice 

 are characterized by the absence of the color producer (C) 



•The term '< latent " has come to have another significance in recent 

 are necessary for the development o/a character. 



494 



