As a mystery writer, I sometimes have to think about blood. I’m not particularly fond of blood. I’m squeamish enough to look away when my own blood is being drawn for lab tests. And I eschew both gore and forensics in my work. However, as Shakespeare knew, it’s hard to talk about murder without mentioning blood.
“Yet who would have thought the old man to have had so much blood in him?” The line is Lady Macbeth’s, the play Macbeth, the victim King Duncan. The spilling of blood is dramatic and shocking, no less in Shakespeare’s day than now. One wonders whether the playwright wrote from personal experience or observation, or if the line came from his superb imagination.
The human body doesn’t really hold such a huge amount of blood in the general scheme of things. Its volume is related to the individual’s body weight and ranges on average somewhere between four and six quarts, or between a gallon and a gallon and a half. In comparison, it takes a gallon of paint to cover a 350 square foot room with seven-foot walls, assuming the room has no doors or windows. That’s a small room, only ten by fifteen feet.
Mystery readers absorb (no pun intended) a certain amount of information about blood from novels. For example, we all know that once a person is definitively dead, blood ceases to flow. So when a shot to the heart kills instantly, less blood is spilled on the scene than those who don’t know this fact might expect. (The absence of blood on the scene might also indicate the body has been moved after death. But that’s another plot device.)
I’ve always read that head wounds bleed copiously. But the information didn’t really sink into my imagination till I attended my fiftieth high school reunion recently. No, nobody paid off an old score by killing a former classmate. But there was an incident involving blood. One of the attendees, who’d become a stooped, balding man with a cane in the half century since graduation, slipped on the marble floor in front of the elevator, unfortunately cracking his head on the sharp right angle where two marble walls met. Within seconds, his white shirt was covered with blood. People rushed to help. (One exasperated woman, trying in vain to get her husband to come back, told the bystanders, “He’s a dentist!”) Luckily, the injured man was not hurt badly enough to call an ambulance. The injury looked a lot worse than it was—because head wounds bleed copiously.
Some writers still get stuff that should be common knowledge wrong. At a recent launch party, I heard a male writer I know read a passage about how a character could not get a bloodstain to come out completely, in spite of the determined application of hot water. Only a guy would make that mistake. Women, who spend their reproductive years periodically (again, no pun intended—well, maybe a little) scrubbing stains out of their undies, know that you use cold water, not hot, on blood.