Answer:
I am perfect with a head perfect without a head; Perfect with a tail perfect without a tail; Perfect with either neither or both.
I am the kind of food monkey likes and people slip on me and fall in cartoons.
In all the world none can compare I am a tiny weaver my deadly cloth so silky and fair.
My first is a heir; My second's a snare; my whole is the offspring of fancy; which I sent out of play upon Valentine's day As a token of love to my Nancy.
Six letters do my name compound; among the aged oft I'm found; The shepherd also by the brook hears me when Leaning on his crook; but in the middle me divide and take the half on either side each backward read a liquor tell ev'ry gay toper knows it well.
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.