( ( ( The purpose ) ( of ( this light ) ) ) ( ( was ( to ( hold ( flies ( non-responsive ( to ( ( ( ( lure ( odors ( in ( the ( downwind end ) ) ) ) ) ( by ( positive phototaxis ) ) ) and ) ( thus ( ( minimize random ) ( flying ( into ( ( the ( upwind end ) ) ( of ( the chamber ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN purpose)) (PP (IN of) (NP (DT this) (NN light)))) (VP (VBD was) (S (VP (TO to) (VP (VB hold) (S (NP (NNS flies)) (ADJP (JJ non-responsive) (S (VP (TO to) (VP (VP (VB lure) (NP (NP (NNS odors)) (PP (IN in) (NP (DT the) (JJ downwind) (NN end)))) (PP (IN by) (NP (JJ positive) (NNS phototaxis)))) (CC and) (VP (ADVP (RB thus)) (VB minimize) (ADJP (JJ random)) (S (VP (VBG flying) (PP (IN into) (NP (NP (DT the) (JJ upwind) (NN end)) (PP (IN of) (NP (DT the) (NN chamber))))))))))))))))) (. .)))
The purpose of this light was to hold flies non-responsive to lure odors in the downwind end by positive phototaxis and thus minimize random flying into the upwind end of the chamber.
(ROOT (S (NP (NNS Phototaxis)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NP (NN movement)) (PP (IN toward) (NP (NN light))))))) (. .)))