As such, the main body 12, by itself, is essentially {HEAD ~ a conduit} through which {TAIL ~ material} may pass 
As such , the main body 12 , by itself , is essentially { HEAD ~ a conduit } through which { TAIL ~ material } may pass
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH