In the witches' chant what do all the images have in common

This is in the wrong category but I will respond anyway. I do love Macbeth. Okay, the binding theme here is that all the witches throw in is EVIL! Elizabethans believed in this stuff and witches as agents of darkness. Consider stuff like poison'd entrails, Toad, snake venom, bat wing.....All can be linked to night animals or biblically "bad" animals (ie. snake). They even dig up Hemlock(poison!!)and, if this isn't bad enough, they dig it in the DARK! There is even some anti-Semitism thrown in the mix (Liver of blaspheming Jew) which I alway must try to explain to my classes.