( ( For ( the ( lens ( to ( be transparent ) ) ) ) ) ( , ( ( the crystallins ) ( ( must ( ( ( be ( closely packed ) ) and ) ( ( transmit light ) ( without scattering ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (DT the) (NN lens) (S (VP (TO to) (VP (VB be) (ADJP (JJ transparent))))))) (, ,) (NP (DT the) (NNS crystallins)) (VP (MD must) (VP (VP (VB be) (ADJP (RB closely) (VBN packed))) (CC and) (VP (VB transmit) (NP (NN light)) (PP (IN without) (S (VP (VBG scattering))))))) (. .)))
For the lens to be transparent, the crystallins must be closely packed and transmit light without scattering.
(ROOT (S (NP (JJ Transparent) (NN matter)) (VP (VBZ transmits) (ADJP (JJ light) (PP (IN without) (S (VP (VBG scattering) (NP (PRP it))))))) (. .)))