"Something that makes you go to sleep when you can't," explained Tad Butler, rather ambiguously.
"When eaten by horses or cattle it is said to put them into deep sleep. The Rockefeller Institute, I believe, is already making an analytical test of the grass."
"Please talk so I can understand it," begged Stacy.
"Yes; those words make my head ache," scowled Ned. "Even the guide is making up faces in his effort to understand."
"He does understand. He understands only too well. For many years this grass has been known. Cows turned out for the day would fail to return at night—"
"To be milked," interjected Stacy.
"And an investigation would disclose them sleeping in some region, where the sleepy grass grew
And the fat boy hummed:
"Down where the sleepy grass is growing."
"Travelers who have tied out their horses in patches of the grass for the night have been unable to continue their journey until the animals recovered from their strange sleep. Thus the properties of the grass became known."