The substantially non dissolvable region remains substantially intact as the dissolving region is progressively dissolved, introducing {HEAD ~ the functional agent} into a flowing stream of {TAIL ~ water} 
The substantially non dissolvable region remains substantially intact as the dissolving region is progressively dissolved , introducing { HEAD ~ the functional agent } into a flowing stream of { TAIL ~ water }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL