32 INHERITANCE OF CHARACTERISTICS IN DOMESTIC FOWL. 



Glareola, Vanellus, Squatarola, Charadrius, Limosa, Machetes, Himantopus) ; 

 second, there is (B) the double web, one-seventh as common, which always 

 occupies the interspaces between the digits ii-iii and iii-iv. 



On another basis, the syndactyl feet may be classified as: (a) toes 

 adherent, web small in extent, and (b) toes distant, web broad. I have 

 found the narrow web only between digits iii and iv. It is one-eighth as 

 common as the broad-webbed type. The broad, double web approaches 

 closely to the type found normally in swans, geese, and ducks. 



Finalh'^, the syndactyl feet may be classified as : a, straight-toed, or (3, 

 curve-toed. Class a is to class (3 in frequency as 2 : 1. In the typical 

 curve-toed syndactyl foot the web between iii and iv is complete to the 

 nails of each; in fact, in extreme cases the nails of the two toes are more 

 or less fused together. From the fused nails the middle toe, being the 

 longer, passes in a curve to the distal end of the metatarsus. The D-shaped 

 interspace between the curved iii and straight iv toe is filled with the web. 

 In other cases the nails are merely approximated and the middle toe is 

 slightly curved. In three instances (4 per cent of all) the outer toe (iv) is 

 curved toward the (straight) median toe (class (3'). 



As stated, the polydactyl offspring trace back their ancestry to No. 

 121; her feet both show the double, broad, straight-toed type (Bba). 

 We shall attempt in the following paragraphs to trace the heredity of her 

 type of polydactylism and of the others that have subsequently arisen. 



B. RESULTS OF HYBRIDIZATION. 



In taking up the results of breeding experiments to test the method of 

 inheritance of syndactylism, it will be best first to give in a table all pens 

 in which the character showed itself, with the frequency of the different 

 types of foot in them (table 23) . 



The history of the syndactyl strain begins with No. 121 $ and in the 

 matings 1 to 8 are given the results of crossing together some of her progeny 

 derived from a normal-toed father. This father was either No. 8a or 1a, 

 both full-blooded Tosa (Japanese Game) fowl and without suspicion in 

 either soma or offspring of syndactyl taint. There is no record of trace of 

 syndactylism in the progeny of 121 X 8a (or 1a); but a shghtly developed 

 condition of syndactylism may very well have been overlooked by me in 

 this F, generation (as I had never thought of such an abnormality), even 

 as I at first overlooked the syndactylism visible in No. 121. But when these 

 F, hybrids were mated together (pen 627, serial Nos. 1 to 8) I got, in 

 the different families, from 10 per cent syndactyl offspring down to none 

 at all. 



At first sight the suggestion arises that, if inheritance is at all MendeUan, 

 the normal condition is dominant and that the heterozygotes throw again, 

 in pen 627, the syndactylous condition. If tliis hypothesis were true it 

 would follow that syndactyls bred together should, sometimes at least, 



