Guard's vanishing bark, on the previous evening, had led up the hillside, behind the house. So, up the hillside I went, scanning the ground eagerly for tracks, or for any sign that might indicate which direction to take. The ground was thickly strewn with pine needles and the search for tracks was fruitless; an elephant's track would not have shown on such ground as that. After a little, though, I did find something that puzzled me. Lying conspicuously near the cattle trail that led upward into the higher hills, was a large piece of fresh beef. Stopping, I turned the meat over cautiously with the toe of my shoe, wondering greatly how it came to be just there. It was cut--not torn--so it could not have been dropped there by any wild beast, but by some person. As I looked attentively at it, some white substance, lying half hidden in a deep cleft in the meat, attracted my attention. I stood still for a long time, studying that bit of beef. That the white substance was poison I had not a doubt. If some one were anxious to kill a dog--like a flash the recollection of Guard's indiscreet charge on Mr. Horton's horse, and of Mr. Horton's speechless rage thereat, came to my mind. An attempt to poison Guard did not strike me, at the moment, as an act indicating anything more than a determination to be revenged on him for the trouble that he had already given Mr. Horton. Afterward, I understood its full significance. A little beyond the spot where I found the poisoned meat, well out of sight from the house, or of any chance passers-by, I came to a tree under which a horse had evidently been recently tethered, and that, too, for a long time. I wondered at this, for, among us, people seldom tether a horse; it is considered an essential part of a cow pony's training to learn to remain long in one place without being fastened in any way. Still, as I reflected, the matter was not one to cause wonder. The ground was torn and trampled by the impatient, pawing hoofs, and I knew very well what horse it was that, for his recent sins, might have been compelled to do penance in this manner. Something over half a mile from our house there was a break in the hills--the beginning of a long and dark ravine that, trending southward, led, if one cared to traverse it, in a tolerably straight course to the far lower end of the valley, near where the Hortons lived.