The following is an excerpt from Ch. 9 of Eric Schlosser's book, Fast Food Nation.  Read it, and answer the question at the end: 

           On July 11, 1997, Lee Harding ordered soft chicken tacos at a Mexican restaurant in Pueblo, Colorado.  Harding was twenty-two years old, a manager at Safeway.  His wife Stacey was a manager at Wendy’s.  They were out to dinner on a Friday night.  When the chicken tacos arrived, Harding thought there was something wrong with them.  The meat seemed to have gone bad.  The tacos tasted slimy and gross.  An hour or so after leaving the restaurant, Harding began to experience severe abdominal cramps.  It felt like something was eating away at his stomach.  He was fit and healthy, stood six-foot-one, weighed two hundred pounds.  He’d never felt pain this intense.  The cramps got worse, and Harding lay in bed through the night, tightly curled into a ball.  He developed bad diarrhea, then bloody diarrhea.  He felt like he was dying, but was afraid to go to the hospital.  If I’m going to die, he thought, I want to die at home.

            The severe pain and diarrhea lasted through the weekend.  On Monday evening Harding decided to seek medical attention; the cramps were getting better, but he was still passing a good deal of blood.  He waited three hours in the emergency room at St. Mary-Corwin Hospital in Pueblo, gave a stool sample, and then finally saw a doctor. It’s probably just a “summer flu,” the doctor said.  Harding was sent home with a prescription for an antibiotic. 

• What does it mean to “pass” blood?  What does the word “stool” mean in this passage?  (Hint:  It’s not a seat with three legs and no back!)