58 INHERITANCE IN POULTRY. 



usually delicate but not otherwise atypical. The barbs are, on the other 

 hand, remarkably long. Thus in a contour feather, from the middle of the 

 dorsal region, whose shaft is 25 mm. long, the prevailing length of barb is 

 35 to 45 mm. The barbs are, moreover, remarkable in that they frequently 

 bifurcate, even repeatedly. In a feather before me, one barb, taken at 

 random, undergoes bifurcation four times. As the branches are not all in 

 one plane, the feather becomes exceedingly fluffy. At the proximal end of 

 the shaft the barbs arise parallel and produce an imperfect web close to the 

 shaft, but marginally the web is lost. Distally on the shaft the barbs arise 

 more irregularly from the shaft, often bifurcating almost immediately, so 

 that no web or vane is formed. The barbs may also anastomose. 



The barbules are not less strikingly modified than the barbs. They attain 

 a length of from i to 2 mm. Moreover, it is not possible here, as in other 

 races, to distinguish between a distal series of barbules carrying a row of 

 hooklets or cilia and a proximal series without booklets but with a folded 

 edge into which the hooklets of the distal barbules catch. This impossibility 

 is due, first, to the fact that the barbules are not in two series merely, but may 

 arise in three planes, or irregularly ; also, morphologically, all the barbules 

 on the barb are alike. They are all segmented like the ordinary distal barbule, 

 and the hooklets are represented by minute thickenings at the end of each 

 segment. As a consequence of this structure the barbs do not hang together 

 to form a vane and the fluffiness is still further exaggerated. 



The quill feathers of the wing (remiges) and tail (rectrices) of the Silky 

 are modified, but to a less degree. Primaries, secondaries, and coverts are 

 all affected. The proximal part of the vane is nearly normal ; the distal part 

 has barbs of twice to thrice the normal length. The barbs may bifurcate 

 repeatedly and even anastomose in the plane of the vane. The barbules also 

 are modified, being much shortened. Proximal as well as distal barbules 

 may carry hooklets, as is seen in the middle part of the feather. In the 

 proximal part of the feather, on the other hand, the proximal barbules are 

 without hooklets. The feathers of the tail have the web even more broken 

 up than those of the wing. 



The silky condition of the feather is a characteristic that is either entirely- 

 new (progressive in de Vries's sense) or possibly latent (in de Vries's sense) 

 in typical fowl, so that its appearance in the Silky is a case of "degression " 

 (de Vries). If the former, we should expect, according to de Vries, the 

 offspring between a Silky and a non-Silky to show a mosaic of the parental 

 feather characteristics and a non-Mendelian inheritance of silkiness ; if the 

 latter, a recessiveness of the varietal characteristic of silkiness and its Men- 

 delian inheritance.* 



*De Vries, 1905, p. 280 : " The character of the species is dominant in the hybrid, while 

 that of the variety is recessive." On the latter of the two assumptions made above, plain 

 plumage is the species eharacter ; silky plumage, the varietal. 



