▁conditions ▁( opt imum : ▁mo ist , ▁warm , ▁sh aded ▁soil ).. ▁When ▁an ▁emb ry on ated ▁egg ▁is ▁ing ested , ▁a ▁R hab dit iform ▁lar va ▁h atch es ▁then ▁pen etr ates ▁the ▁wall ▁of ▁the ▁g astro int est inal ▁tract ▁and ▁enters ▁the ▁blood ▁stream . ▁From ▁there , ▁it ▁is ▁carried ▁to ▁the ▁li ver ▁and ▁heart , ▁and ▁enters ▁pul mon ary ▁circul ation ▁to ▁break ▁free ▁in ▁the ▁al ve oli , ▁where ▁it ▁grows ▁and ▁mol ts . ▁In ▁three ▁weeks , ▁the ▁lar va ▁passes ▁from ▁the ▁resp ir atory ▁system ▁to ▁be ▁c ough ed ▁up , ▁sw allowed , ▁and ▁thus ▁reaches ▁the ▁small ▁int est ine , ▁where ▁it ▁m atures ▁to ▁an ▁adult ▁male ▁or ▁female ▁w orm . ▁F ert il ization ▁can ▁now ▁occur ▁and ▁the ▁female ▁produces ▁as ▁many ▁as ▁ 2 0 0 , 0 0 0 ▁eggs ▁per ▁day ▁for ▁ 1 2 – 1 8 ▁months . ▁These ▁fert il ized ▁eggs ▁become ▁inf ect ious ▁after ▁two ▁weeks ▁in ▁soil ; ▁they ▁can ▁persist ▁in ▁soil ▁for ▁ 1 0 ▁years ▁or ▁more . ▁ ▁The ▁eggs ▁have ▁a ▁li pid ▁layer ▁which ▁makes ▁them ▁resist ant ▁to ▁the ▁effects ▁of ▁ac ids ▁and ▁alk alis , ▁as ▁well ▁as ▁other ▁chemical s . ▁ ▁This ▁res ili ence ▁helps ▁to ▁explain ▁why ▁this ▁n emat ode ▁is ▁such ▁a ▁u bi quit ous ▁par as ite .