SILVER BLOOD
"Wolfsbane doesn't kill. What do you mean they are supposed to be dead?"
Dr. Riley sighed. “True, wolfsbane doesn't kill, but silver does—at least when left for a longer period in the bloodstream."
I took the other tube from his hand and surveyed it. "But there isn't any silver here. How would they have gotten silver?" I questioned.
“There is, in that one, if you look closely," he gestured for the tube in Harry's grip, the one that contained the wolfsbane we had seen earlier.
Harry raised the tubes against the sun while he squinted. "I do see something in it, but barely."