The amount of reducing substance and {HEAD ~ the period} of time for interaction are so adapted to obtain {TAIL ~ the product} desired, whereafter the blood and plasma, respectively, are optionally fractionated in a known manner 
The amount of reducing substance and { HEAD ~ the period } of time for interaction are so adapted to obtain { TAIL ~ the product } desired , whereafter the blood and plasma , respectively , are optionally fractionated in a known manner
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH