ORIGIN OF A POLYDACTYLOUS RACE OF GUINEA-PIGS. 2 I 



4. PROGENY OF THE THIRD POLYDACTYLOUS GENERATION. 



Continuing to trace the history of the polydactylous race in the male 

 line, we may notice that the sires of the next generation of young consisted 

 of four sons of 193. Two of these were own brothers, viz, 628 and 

 ^809 (see table i). The other two were half-brothers to these two and to 

 each other. They were (^635 and c?7ii. The young of these four males 

 are classified as regards the extra-toe character in tables 4 to 7 (see pages 

 25 and 26). An examination of these tables shows for 809 an increase of 

 potency over that of his father, <$ 193; J 1 711 shows a potency very similar 

 to that of his father, but the other two males, J 1 628 and 635, are clearly 

 inferior to their father in potency, their average grades being about 34 and 

 38 respectively, while that of their father was 46. 



5. PROGENY OF THE FOURTH POLYDACTYLOUS GENERATION. 



The sires of the next generation consisted of six males, four of which 

 were sons of the best male (809) of the previous generation, while one was 

 a son of ^628, and one a son of <^7n. Considering first the four sons 

 of <$ 809 (table 7), we notice that three of them, $ 954 (table 8), J 1 1140 

 (table 10) and $ 1264 (table 13), are clearly inferior to their father in 

 potency. The fourth male, $ 1263 (table 12), makes a somewhat better 

 showing than his father, though two of the possible groups of mothers (F 

 and N) are wholly unrepresented among his mates and their values can 

 only be roughly estimated by interpolating values, while two other groups 

 are very inadequately represented. Yet all the data available agree in 

 showing high potency on the part of this male. Out of a total of eighty-three 

 young which he has sired, only one has been three-toed. 



Male 1003 (table 9) has a record similar to that of his father, $ 628 

 (table 4), but on the whole better. It is noteworthy that neither of these 

 animals gave polydactylous offspring when mated to unrelated normal 

 females, though by polydactylous mothers they had a good proportion of 

 polydactylous young. 



Male 1165 (table u), also, has a record like that of his father, $ 711 

 (table 6). By unrelated normal (N'~) females he produced offspring grad- 

 ing 10 as regards the extra-toe character, his father's offspring by the same 

 group of mothers grading 8. By matings with polydactylous mothers, both 

 father and son have produced offspring grading below those of <$ 809 and 

 of J 1 1263. 



