The Genetic Factors in the Development 



of the Housemouse, which Influence the 



Coat Colour, 



with Notes on such Genetic Factors in the Development of 

 the other Rodents. 



By Arend L. Hagedoorn, XtriitiLS le Buisson. 



Introduction. 



Experiments with rodents to determine the relation of the different 

 colours to each other have been made by different authors since the 

 rediscovery of Mendel's work. Most of these experiments have been 

 made by Allen, Bateson, Castle, Crampe, CuEnot, Darbishike, 

 Davenport, Doncaster, Durham, Guaita, Haacke, Hurst, 

 Morgan, Mudge, Przibram, Schuster, Sollas and Woods. 



Almost without exception it has been found by all, that different 

 colours are produced as the result of combinations of several trans- 

 mittable factors in the germ, which factors can either be present or 

 absent. 



It is my object in this paper to speak of the relation of these 

 factors toward one another, and to show the influence which each 

 one of the nine factors which I have personally studied has on the 

 ultimate colour of the animal in which they are present. 



In doing so I will also draw into account what is known about 

 the genetic factors influencing colour in the other domesticated rodents, 

 the brown rat, the cavy, and the rabbit. 



Personally I have only done little work with cavies and rabbits, 

 but I think it interesting to show that a great number of genetic 

 factors are indentical in the four species. As will be seen from this 

 paper, the range of colours known in the different animals does not 

 differ so much because in one there are factors present which are 

 not present in the others; probably in each of the four groups the 



Induktive Abstammungs- und Vererbungslehre. VI. 7 



