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