1) To remove warts, go to a graveyard at midnight and throw a dead cat at the devil when he appears.
2) Put quicksilver in bread and set the bread to float in a river to find a drowned body.
3) Worm crawling across your legs means you will get new clothes.
4) Bracelet of rattlesnake rattles will protect you from cramps.
5) Friday is an unlucky day.
6) Haunted houses exist.
7) A cross on the wall wil protect you from a ghost.
8) Howling dog = death.
These superstitions are important to Twain's themes in this story. Consider these words from the preface:
"The odd superstitions touched upon were all prevalent among children and slaves in the West at the period of this story -- that is to say, thirty or forty years ago. Although my book is intended mainly for the entertainment of boys and girls, I hope it will not be shunned by men and women on that account, for part of my plan has been to try to pleasantly remind adults of what they once were themselves, and of how they felt and thought and talked, and what queer enterprises they sometimes engaged in."
Twain is painting a portrait of an area and showing all the regional beliefs that control behavior in that area. He is also demonstrating the hypocrisy and illogical nature of human behavior through the superstitions. As readers, our attention is called to the fact that these are silly beliefs. However, they do control the behavior of characters, showing how ridiculous humans can be.
Warts: Tom and Huck beleive thorouglyand do not question the implausible cures for warts they have grownup hearing.
Dead cats: believed to be powerful and thererefore useful.
Howling dogs: thought to portend death: First Tom and Huck think the omen is for them, but then see the dog howling at Muff Potter. THe boys don't think there is anything the can do for Muff since they truly believe in the superstition.
Among the many local superstitions are one that says that, accompanied by the proper rituals, dead cats cure warts (Chapter VI); another is "a prevailing juvenile superstition that to cross water baffle(s) pursuit" (Chapter VIII). A frightening superstition which haunts Tom and Huck after they witness the murder of Dr. Robinson is that a stray dog can point out whom death will strike next (Chapter XI). Tom describes a colorful superstition which "all his comrades had always looked upon as infallible...if you buried a marble with certain necessary incantations, and left it alone a fortnight...you would find that all the marbles you had ever lost had gathered themselves together there" (Chapter VIII).