Alcatraz had wakened suddenly and driven both heels at his neighbor.  Luckily he missed his mark, but the starter ran across the track and lessoned Cordova with a raised finger.  Then he went back; there was a breath of waiting; the gun barked!

The answer to it was a spurt of low-running horses with a white cloud of dust behind, and Corson laughed aloud in his glee.  Every one of the group in the lead was a range horse; the Coles mares were hanging in the rear and last of all, obscured by the dust-cloud, Alcatraz ran sulkily.

“But you wait!” said Marianne, sitting tensely erect.  “Those ponies with their short legs can start fast, but that’s all.  When the mares begin to run—­Now, now, now!  Oh, you beauties!  You dears!”

The field doubled the first jagged corner of the track and the bay mares, running compactly grouped, began to gain on the leaders hand over hand.  Looking first at the range hosses and then at the mares, it seemed that the former were running with twice the speed of the latter, but the long, rolling gallop of the bays ate up the ground, and bore them down on the leaders in a bright hurricane.  The cowpunchers, hearing that volleying of hoofbeats, went to spur and quirt to stave off the inevitable, but at five furlongs Lady Mary left her sisters and streaked around the tiring range horses into the lead.  Marianne cried out in delight.  She had forgotten her hope that the mares might not win.  All she desired now was that blood might tell and her judgment be vindicated.

“They won’t last,” Corson was growling, his voice feeble in the roar of the excited crowd.  “They can’t last that pace.  They’ll come back after a while and the ponies will walk away to the finish.”

“Have you noticed,” broke in Mrs. Corson, “that the poor old faded chestnut seems to be keeping up fairly well?”

For as the bay mares cut around into the lead, Alcatraz was seen at the heels of the range horses, running easily.  It seemed, with a great elastic stride.

“But—­but—­it’s not the same horse!” Marianne gasped.

To be sure, Alcatraz in motion was transformed, the hollows among his ribs forgotten, and the broken spirit replaced by power, the electric power of the racer.

“It looks very much to me as if the Mexican is pulling that horse, too,” said Marianne.  For Cordova rode with legs braced, keeping a tight pull that bent the head of Alcatraz down.  He might have served for a statue of fear.  “And notice that he makes no effort to break around the range horses or through them.  What’s the matter with him?”

At seven furlongs the mares were in a group of themselves, lengths in front and drawing away; the heads of the cowponies were going up, sure sign that they were spent, and even Corson was gloomily silent.  He was remembering his bet against Lady Mary, and lo, Lady Mary was breezing in front well within her strength.  One glance at her pricking ears told an eloquent story.  Near them Marianne saw big Colonel Dickinson capering.  And the sight inspired a shrewd suspicion.  What if he knew the reputation of Alcatraz and to secure his bets on Lady Mary, had bribed Cordova at the last moment to pull his horse.  Certainly it seemed that was what the Mexican was doing.