means adapted to form a seal with the collection tube as {HEAD ~ the separator tube} is pushed into {TAIL ~ the collection tube}, 
means adapted to form a seal with the collection tube as { HEAD ~ the separator tube } is pushed into { TAIL ~ the collection tube } ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH