M A N Eggs In f«a -f111'§~~~;------___; )tll. _~ Emb,yonatfd Eoo with 2nd s~g l. 1rv;l (lnfe<:tlvc stag) (d L>gno,rc 1>9) Advane<>d c;lea11agc EXTERNAL ENVIRONMENT Illustration 15. 3 The Life Cycle of,o. scarls lumbrlcoides 361 r 