THE 



AMERICAN NATURALIST 



Vol. XLVII June, 1918 No. 558 



HEREDITY OF TRICOLOR IN GUINEA-PIGS 



H. D. GOOD ALE AND T. H. MORGAN 



We undertook the following experiments with guinea- 

 pigs in order to see whether the tricolor and bicolor con- 

 ditions described by Galton for Basset hounds could be 

 brought in line with modern Mendelian interpretation. 

 According to his recent paper, Castle was led to study 

 the same problem from the same point of view. He has 

 published a brief and important statement summarizing 

 his results. 



Our work was begun in 1908 and has gone on steadily, 

 but slowly, since then, until a contagious disease de- 

 stroyed the stock. It soon became evident that the prob- 

 lem is one of extreme complexity, and for its complete 

 solution a much more elaborate and better planned series 

 of experiments will be necessary. We hope that our re- 

 sults, fragmentary though they be, may serve to put on 

 record the actual facts observed and that certain pro- 

 visional suggestions that are made will be further tested. 



The inheritance of color in guinea-pigs has been ex- 

 tensively studied by Castle. Animals with a coat of 

 uniform color may be agouti, black, yellow (red) or 

 albino. We are concerned here only with black, red and 

 white (not necessarily albino). When black guinea-pigs 

 are crossed to red ones the offspring are black, or black 

 with traces of red. Castle points out that the F t black 

 is not so dark as in the pure black strain, but shows evi- 



