{HEAD ~ a movable valve member} adapted to seat on {TAIL ~ said seating portion} on one side of said opening so as to close said valve opening in the presence of serum or plasma in said tubular member, 
adapted to seat on
{ HEAD ~ a movable valve member } adapted to seat on { TAIL ~ said seating portion } on one side of said opening so as to close said valve opening in the presence of serum or plasma in said tubular member ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH