oj INHERITANCE in GUINEA-PIGS. 



VARIATIONS OF SEPIA. 



We find rather more overlapping of distributions among the sepias 

 tli:m among the yellows when different genetic constitutions are com- 

 pared. Nevertheless there are significant differences in the means. 

 The groups ( !j< ,|. ( \\(\. and C r C r with means from sepiaj to sepia 21 , 

 nearly black, average distinctly darker than groups C d C a and C r C a with 

 mean- of >epia, - :m( l Bepia4.7, respectively. The case is quite different 

 from yellow dilution in which C d C r and C d C a have the same effect (or 

 nearly bo) contrasting with C d C d . C r seems to be essentially identical 

 with ( ',; in effect on black, but like C a in effect on yellow. 



1 ( n tint her analysis we must compare stocks. In the miscellaneous 

 stock the average for C d C a is sepia 5 . 5 . When this stock is crossed with 

 albinos of BW stock the average of the young— again C d C a — is sepia 43 . 

 When these are crossed again with BW albinos the average becomes 

 ia, 5 . The darkening influence of the BW stock is apparent. The 

 South American stock also has a darkening influence with an average 

 of sepia 4 o. We find a similar difference between the miscellaneous and 

 South American stocks among the homozygotes. 



The comparison of C d C a with C r C a within the same stock (South 

 American) yields a slight but probably significant difference (C d C a , 

 >epia, ,; C r C a , sepia 47 ). Thus there is a difference of 0.5 with a prob- 

 able error of 0.12. It is certain that some of the red-eyed sepias have 

 been paler than any black-eyed sepia. 



If there is a real difference here, we w r ould expect C r C r to be lighter 

 than (\\(\\ or C d C n but the 4 individuals known to be C r C r give the 

 darkest average of any array. They were not, however, a random 

 sample and, further, were either pure lea or F 2 IcaXBW and hardly 

 t<> be compared in stock with those known to be C d C d or C d C r . For 

 the present CdC<j, C d C r , and C r C r may be considered identical in effect 

 • in black fur. 



As in the case of yellows, the most critical test of the hypothesis of 

 imperfect dominance is the success of prophecy. In litters which 

 should give both C d C d and C d C a , the 2 darkest tested (sepia 2 ) both 

 proved to be homozygous, while 8 others (sepia 4 to sepiaj proved to 

 transmil albinism. Among those which when graded might be either 

 ( ( r or ( ,,( ' . 1 8 were tested. There is some overlapping of ranges, but 

 those which were found to transmit red-eye average very distinctly 

 darker than those which transmitted albinism. Four were tested in an 

 I from red-eve by albino. The 3 dark ones, including 2 which were 

 actually as black as blacks of the BW race, proved to be C r C r , while 

 the other, Bepia*, had albino young and was therefore C r C a . 



Table 40 shows thai in the case of the sepias there is a very perceptible 

 darkening with age. This is shown in all groups except the homozy- 

 gous red-eyes, which were practically jet black to begin with. Another 

 interesting point brought out is a race difference in the amount of 



