ian ▁Ant ar ctic ▁Ex ped ition ▁( 1 9 1 1 - 1 4 ) ▁under ▁Douglas ▁M aw son . ▁ ▁References ▁ ▁Category : Head lands ▁of ▁George ▁V ▁Land <0x0A> </s> ▁Fe ul gen ▁st ain ▁is ▁a ▁st aining ▁technique ▁discovered ▁by ▁Robert ▁Fe ul gen ▁and ▁used ▁in ▁hist ology ▁to ▁identify ▁chrom os om al ▁material ▁or ▁DNA ▁in ▁cell ▁spec im ens . ▁It ▁is ▁dark ly ▁st ained . ▁It ▁depends ▁on ▁acid ▁hydro ly s is ▁of ▁DNA , ▁therefore ▁fix ating ▁agents ▁using ▁strong ▁ac ids ▁should ▁be ▁avoided . ▁ ▁The ▁spec imen ▁is ▁subject ed ▁to ▁warm ▁( 6 0 ▁° C ) ▁hydro ch lor ic ▁acid , ▁then ▁to ▁Schiff ▁re agent . ▁In ▁the ▁past , ▁a ▁sul f ite ▁rin se ▁followed , ▁but ▁this ▁is ▁now ▁considered ▁unnecessary . ▁Option ally , ▁the ▁sample ▁can ▁be ▁counter st ained ▁with ▁Light ▁Green ▁SF ▁yellow ish . ▁Finally , ▁it ▁is ▁de h yd r ated ▁with ▁eth an ol , ▁cleared ▁with ▁x yl ene , ▁and ▁mounted ▁in ▁a ▁res in ous ▁medium . ▁ ▁DNA ▁should ▁be ▁st ained ▁red . ▁The ▁background , ▁if ▁counter st ained , ▁is ▁green . ▁ ▁The ▁Fe ul gen ▁reaction ▁is ▁a ▁semi - quant itative ▁technique . ▁If ▁the ▁only ▁al de hy des ▁remaining ▁in ▁the ▁cell ▁are ▁those ▁produced ▁from ▁the ▁hydro ly s is ▁of ▁DNA , ▁then ▁the ▁technique ▁is