168 Degeneration in the Ostrieh 



small as to be almost buried in the integument, while on the left toe it 

 was wholly lacking. 



TABLE XL 

 Breeders : 



South African cock, No. 226 No claw 



Cross hen, No. 167 Claw on right toe integumental, no claw on left 



Chicks : 



Eight— Nos. 1, 3, 5, 7 to. 11 No claw 



One — No. 2 ... ... ... Integumental claw on right, no claw on left 



Two — Nes. 4, 6 ... ... Integumental claws on both right and left 



Out of eleven chicks eight have no claws, two have a very small one 

 on both right and left toes, and one resembles the hen parent in having 

 a small claw on the right and none on the left. Clearly the claw factor 

 in the hen is in a weak fluctuating state, and either fails to gain its 

 normal proportion of expressions in the progeny or has but a feeble 

 result. We have a complete departure from the more or less rigid 

 Mendelian proportions, but only what might be expected where the 

 factors are in a variable, degenerative state. 



Though the claw is normally dominant in heterozygous proportions, 

 in the series below this is very far from being the case. Out of ten 

 chicks hatched from the same clawed cock as in Table IX, but with 

 a different hen, only one was provided with a claw, and then only on 

 the right toe, not on the left. The progeny in Table IX represent a 

 weak factorial expression, while below it practically Mis altogether. 

 As already established in connection with the wing-quills, Mendelian 

 proportions are not necessarily maintained in crosses where degene- 

 ration is in progress. Factors or factorial systems near their limit of 

 expression may or may not gain expression in the progeny, and so 

 disturb the expected ratio. 



TABLE Xll. 

 Breeders : 



North African cock, No. 84 Claw medium 



North African hen, No. 116 No claw 



Chicks : 



Nine — Nos. 1 to 9 No claw 



One — No. 10 ... ... Medium claw on right toe, none on left 



From what is given above, there can be no question that the claw 

 on the fourth toe of the ostrich is in a variable degenerative phase 

 at the present time, while its rare occurrence in a mixed assemblage 

 shows that complete loss has freely taken place in the past. The 

 various degrees of expression in the chicks hatched are eloquent testi- 

 mony of corresponding factorial variation in the germ plasm, so far as 



