us . ▁ ▁A ▁generalized ▁scheme ▁for ▁som atic ▁cell ▁hy brid ization ▁may ▁be ▁described ▁as ▁follows . ▁App ropri ate ▁human ▁and ▁mouse ▁cells ▁are ▁selected ▁and ▁mixed ▁together ▁in ▁the ▁presence ▁of ▁in activ ated ▁Send ai ▁virus ▁or ▁P EG ▁to ▁promote ▁cell ▁fusion . ▁After ▁a ▁period ▁of ▁time , ▁the ▁cells ▁( a ▁mixture ▁of ▁man , ▁mouse ▁and ▁' hy brid ' ▁cells ) ▁are ▁pl ated ▁on ▁a ▁select ive ▁medium , ▁e . g ., ▁H AT ▁medium , ▁which ▁allows ▁the ▁multiplication ▁of ▁hy brid ▁cells ▁only . ▁ ▁Several ▁cl ones ▁( each ▁derived ▁from ▁a ▁single ▁hy brid ▁cell ) ▁of ▁the ▁hy brid ▁cells ▁are ▁thus ▁isolated ▁and ▁subject ed ▁to ▁both ▁c yt ogen etic ▁and ▁appropriate ▁bio chem ical ▁anal ys es ▁for ▁the ▁detection ▁of ▁en zym e / ▁protein / tra it ▁under ▁investigation . ▁An ▁attempt ▁is ▁now ▁made ▁to ▁correlate ▁the ▁presence ▁and ▁absence ▁of ▁the ▁trait ▁with ▁the ▁presence ▁and ▁absence ▁of ▁a ▁human ▁chrom os ome ▁in ▁the ▁hy brid ▁cl ones . ▁ ▁If ▁there ▁is ▁a ▁perfect ▁correlation ▁between ▁the ▁presence ▁and ▁absence ▁of ▁a ▁human ▁chrom os ome ▁and ▁that ▁of ▁a ▁trait ▁in ▁the ▁hy brid ▁cl ones , ▁the ▁gene ▁gover ning ▁the ▁trait ▁is ▁taken ▁to ▁be ▁located ▁in ▁the ▁concerned ▁chrom os ome . ▁ ▁The ▁H AT ▁medium ▁is ▁one ▁of ▁the ▁several ▁select ive ▁media ▁used ▁for ▁the ▁selection ▁of ▁hy brid ▁cells