m. 640J DATA COXCEIiXlXG LIXKAGE IN MICE 417 



The deviation from the normal distribution is less than 

 the probable error and therefore not significant. 



In the repulsion series the genes for agouti and black- 

 eyed-white entered separately into the Fj zygote. When 

 back crossed these agouti black-eyed-white young gave 

 the distribution recorded in the repulsion series of Table 

 II opposite "new data." Here the cross-overs number 

 109, and the non-cross-overs 121, whereas equal numbers 

 are expected. This is a fair distribution for the small 

 numbers raised. Combining the new data on the recipro- 

 cal crosses gives 285 cross-overs, or 48.14 per cent, of the 

 592 young raised, with a probable error of ± 1.38. 



Combining Dunn's data with the new data, there are 

 543 and 581 animals in the cross-over and non-cross-over 

 classes, respectively. The cross-over percentage is 48.30 

 ± 1.00. The deviation from the normal distribution is 

 less than twice the probable error. The data, separately 

 and combined, clearly show the independence of the two 

 genes. 



The Relation of Black-eyed-white Spotting to 

 Pink-Eye 



Previous work by Tlaldane et al. has showm pink-eve 

 to b.' linked with albinism. Detlefsen (1916) described 

 bl;ick-c> ('(I-w liitc mice carrying pink-eye, which resembled 

 alliiii(i>. Imt tlir ii'enes segregated in the second genera- 

 tion. Xo hack-crosses were made in his experiments. 

 No direct intensive crosses hitherto published have dealt 

 with the possible linkage relation between these genes. 



In a cross made for such a study, the genes for black- 

 eyed-white spotting and pink-eye entered separately. 

 Accordingly the V■^ gametes should give equal numbers 

 of the parental non-cross-over types (WP and wp), and 

 of the new cross-over combinations (Wp and wP), if the 

 genes AV and \^ aiv independent. H" linked, they should, 

 in \\u' bai'k-cio->, >ho\\- rrpul.-ion and the foraier combi- 

 nation^ 1.. ii, nf ih,. !;,ti,T. In Table III oppo- 



site "new data" of the repulsion series is shown the dis- 



