J. E. DUERDEN 167 



fluctuate, not only between individuals but also between the right 

 and left sides. 



TABLE VIII. 



Breeders : 



North African cock, No. 78 Weak claw 



North African hen, No. 44 No claw 



Chicks : 



Three— Nos. 352, 353, 354 No claw 



Two— Nos. 340,356 ... Eight claw strong, left weak 



One — No. 357 Both claws strong 



The varying manner in which the claws may express themselves in 

 progeny from the same breeding pair is further illustrated in the next 

 Table. . 



TABLE IX. 



Breeders : 



North African cock. No. 84 Claws medium 



North African hen, No. 87 No claw 



Chicks: 



Two— Nos. 342, 343 ... No claw 



Two — Nos. 345, 346 ... Claws scarcely showing, integumental 



One — No. 241 Bight claw medium, left weak 



One — No. 244 ... ... Both claws medium 



Where one parent is clawed and the other not, the Mendelian 

 proportion for heterozygotes is not always maintained in the progeny, 

 as shown below, where the hen of the previous series is mated with a 

 different cock. 



TABLE X. 



Breeders : 



North African cock, No. 284 Claws medium, but abnormally upturned 



North African hen. No. 87 No claw 



Chicks : 



Six — Nos. 1 to 3 ; 5 to 7 ... No claw 



Two — Nos. 4, 8 ... ... Claws medium and upturned 



One — No. 9 . . . ... ... Upturned claw on right, none on left 



Out of nine chicks hatched, only two were provided with full claws 

 and one with but a single claw, instead of the Mendelian expectation 

 of four or five fully clawed. The irregular, upturned form in the parent 

 cock may possibly be an indication that the genetic factor was not of 

 normal stability. 



The variable result from an obviously weak factorial representation 

 is still better illustrated in the following series. That the genetic factor 

 was actually weak and on the verge of failing to express itself may be 

 inferred from the fact that on the clawed parent the right claw was so 



11—2 



