Reference for Chullin 245:10

המרגיל כולו חבור לטומאה ליטמא ולטמא

[THE HIDE] IS REGARDED AS A CONNECTIVE [WITH THE FLESH] IN RESPECT OF UNCLEANNESS, FOR THE FLESH TO CONTRACT UNCLEANNESS OR CONVEY UNCLEANNESS, UNTIL SO MUCH [OF THE] HIDE HAS BEEN FLAYED AS CAN BE TAKEN HOLD OF;<span class="x" onmousemove="('comment',' Until this much has been flayed that portion which has actually been flayed is not regarded as entirely disconnected from the flesh but rather as a 'handle' which conveys uncleanness to and from the flesh. Once this extent (- for the measure v. Gemara -) has been flayed the hide is regarded as disconnected and can no longer serve as a handle.');">⁷</span>

Jastrow

Jastrow

Jastrow