COAT-COLOR IX HYBRIDS OF PEROMYSCl'S EREMICVS. 51 



the hair and the percentage of B hairs (mean = -(- 1.68), as 

 well a- 1. ctween the length of the agouti band and the percentage 

 of /' hairs (mean -{-.240), while negative correlations were 

 found between length of hair and percentage of D hairs ( - - .187) 

 and between length of agouti band and percentage of D hairs 

 i .221 ). Such relations suggest the possibility that certain ele- 

 ments of the siibspecific complex of characters depend upon fac- 

 whirh are cl.^ely linked, or that they may have, in part, a 

 I basis. That this is not true of all the characters 

 distinctive of a subspecies is shown by the case of "black" and 

 i pig" ' 11. above referred to, and by various other facts 



derived from a study of the present and of previous series of 

 animals. 



Where correlation between two characters has appeared, whether 

 tive or negative, there appears to be a tendency for 

 this correlation to be greater in the P., series of hybrids than in 

 1 ; ,. While such a condition has not been invariable, the ten- 

 dency seems to be a real one and not due to accident. 1 Several 

 nf tin >e differences taken singly, are of considerable statistical 

 pnihahlity. This phenomenon is. of course, in harmony with the 

 view that the increased variability of the F., generation results, in 

 part at least, from mcndelian segregation. Whether the correla- 

 tion of two characters be due to their having some common fac- 

 >. or to their being dependent on linked factors, the re- 

 sult nf segregation would be to increase the correlation between 

 them. 



VI. CONCLUSIONS. 



In a previous paper- the authors have discussed the behavior 

 in heredity of small deviations from bilateral symmetry among 

 paired hme<. The two outstanding results of that study were (i) 

 that such departures from bilateral symmetry were not inherited. 

 but that i J i we none the less met with the customary increase in 

 the variability of these characters in the F.. generation of a sub- 



i In .i : :! study of Pcromysctis hybrids (Jr>tirn. E.r/ 1 . Zoology, Oct., 



e was found for such an increase in correlation in the 



nl hylirii! generation. Several other correlations which were computed 



sul.-t -.jin -n:l\ li.ive rendered such an increase more probable, even for these 



bcr. 



