(S (S (BASENP (DT The) (NN bacteria)) (VP (MD could) (VP (VB have) (VP (VBN been) (VP (VP (VP (VBN carried) (PP (IN by) (BASENP (JJ wild) (NNS animals)))) (PP (IN from) (BASENP (DT the) (NN cattle) (NN ranch)))) (PP (TO to) (BASENP (DT the) (NN spinach) (NN field)))))))) (PERIOD .))