( It ( ( ( is only ) ( in ( ( the ( lower organisms ) ) ( ( ( ( ( that ( ( ( ( the ( same tissue ) ) or ) organ ) ( can ( perform ( different functions ) ) ) ) ) , ) ( whilst ( ( in ( the vertebrates ) ) ( ( the stomach ) ( ( can only ) ( serve ( for ( ( ( digestion , ) ( ( the lungs ) ( for oxygenation ) ) ) , ) ) ) ) ) ) ) ) and ) ( so on ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (ADVP (RB only)) (PP (IN in) (NP (NP (DT the) (JJR lower) (NNS organisms)) (SBAR (SBAR (IN that) (S (NP (NP (DT the) (JJ same) (NN tissue)) (CC or) (NP (NN organ))) (VP (MD can) (VP (VB perform) (NP (JJ different) (NNS functions)))))) (, ,) (SBAR (IN whilst) (S (PP (IN in) (NP (DT the) (NNS vertebrates))) (NP (DT the) (NN stomach)) (VP (MD can) (ADVP (RB only)) (VP (VB serve) (PP (IN for) (NP (NP (NN digestion)) (, ,) (NP (NP (DT the) (NNS lungs)) (PP (IN for) (NP (NN oxygenation)))) (, ,))))))) (CC and) (SBAR (IN so) (FRAG (PP (IN on)))))))) (. .)))
It is only in the lower organisms that the same tissue or organ can perform different functions, whilst in the vertebrates the stomach can only serve for digestion, the lungs for oxygenation, and so on.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NP (JJ different) (NNS types)) (PP (IN of) (NP (NNS tissues)))) (VP (VBP work) (ADVP (RB together)) (S (VP (TO to) (VP (VB perform) (NP (DT a) (JJ unique) (NN function)))))))) (, ,) (NP (PRP they)) (VP (VBP form) (NP (NN organ))) (. .)))