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Re: Baby insulation (fwd)



[Jeff appears to have sent his question directly to Royan, but since
 the response seems relevant to on-going discussions, and since Jeff
 has been on the opposite side of this fence before I figured I'd pass
 along the response... -- MR ]

Jeffrey Martz did inquire:

>> Bear in mind that modern feathers have a blood supply while they are
>> growing out. Perhaps this is an adaptation from a fuller supply?

>     Are the blood vessels confined to the rachis or do they brach out
>into the barbules?

 From "The Complete Bird Owner's Handbook" Gary A. Gallerstein D.V.M.

Soon afterwards the emerging feather, called a pin or blood feather,
appears, werapped in a protective keratin sheath. Each of these young
growing feathers contain their own artery and vein. If this new
feather is damaged or broken, bleeding will occur. When the feather is
completely groown in, its blood supply "dries up". The sheath then
falls off or is removed by the bird. The feather, now fully mature, is
essentially a dead structure.

This is why I question the feathers from scales theory as I don't know
of any scales with a blood supply.

Royan
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