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