MISCELLANEA. 



I. Note on the Results of Crossing Japanese Waltzing Mice with 



European Albino Races. 



By a. d. darbishire. 



The breeding experinients, of wliich this i« only :i preliiniiuiry account, were uudertakcn at 

 Professor Weldon's Suggestion with the object of throwing some light oii the problem of 

 Heredity, and especially on the Laws of Mendel. 



For this purpose crosses were made between the Japanese " waltzing " niouse and the cuninion 

 albino mouse. These animals were used because they have already Ijeen made the subject 

 of similar experiments, the results of which have been recorded first by Haacke*, who gives no 

 numerical statements, but says that when a Japanese mouse is crossed with an albino the 

 offspring is wild-colovu-ed or black, sometimes with a white spot on the forehead or belly, 

 and secondly by von Guaitat who gives elaborate tables, showing that the first cross-bred 

 generation has always the colour of wild mioe, white individuals of subsequent generations 

 are white, black, brown or piebald. The cross-bred forms of the first generation did not 

 exhibit the " dancing " niovements of the Japanese mice, while a certain proportion of individuals 

 in subsequent generations did so. BatesonJ has suggested that the results obtained by these 

 observers, and by others, "show an essential harmony in the fact that both found alhino 

 an obvious recessi\'e, pure alinost without excepticjn, while the coloured forms show various 

 phenomena of dominance." Lack of uniformity in the characters of the first cross-bred generation 

 is elsewhere attributed by Batesou to impurity in the stock used§. 



The experiments were made, then, in order to answer two simple questions : 



(1) Does the first generation of cross-bred individuals, produced by pairing alliino and 

 Japanese waltzing mice, exhibit such a uniformity of colour as will justify us in considering that 

 Mendel's Law of Dominance applies to it ? 



(2) Does the Mendelian Law of Segregation apply to the ofispring of hybrids resultiug 

 from such crosses ? 



* "Über Wesen, Ursachen imd Vererbung von Albiuismus, etc.," Biologisches Cenlnilblatt, xv. 

 1895, pp. 44 et .s-,t/. 



t "Yersuche mit Kreuzungen von verschiedenen Kassen des Hausmaus," Berichte d. natuiforsch. 

 Gesellsch. Freibnrg, x. (1898) pp. 317-332, and xi. (1900) pp. 131-138. 



t Mendel's Principles nf Heredity, Cambridge, 1902, p. 174. 



§ Report to the Evolution Committee of the Royal Society, 1902, p. 145. 



