No Poisoned Arrows
Maj. Powell, who has carefully investigated the subject, comes to the conclusion that poisoned arrows have never been used by American Indians. The belief of Indians is that diseases do not come from natural causes, but are the work of evil spirits. Hence they would not be likely to conceive the idea of inoculating disease by means of poisoned substances. They do not know, for example, that rattlesnake poison comes from a sack in the reptile's jaw. What they call "poisoned arrows" or "medicine arrows" are arrows to which supernatural qualities are supposed to have been imparted by incantations.
Bismarck Semi-Weekly Tribune, 5-30-1877