In sheer skill and brain-work and generalship, Lad was wholly Rex's superior, but these served him ill in a death-grapple. With dogs, as with human pugilists, mere science and strategy avail little against superior size and strength and youth. Again and again Lad found or made an opening. Again and again his weakening jaws secured the right grip only to be shaken off with more and more ease by the younger combatant. Again and again Lad "slashed" as do his wolf cousins and as does almost no civilized dog but the collie. But the slashes had lost their one-time lightning speed and prowess. And the blunt "rending fangs" scored only superficial furrows in Rex's fawn-colored hide. There was meager hope of reaching home alive. Lad must have known that. His strength was gone. It was his heart and his glorious ancestry now that were doing his fighting--not his fat and age-depleted body. From Lad's mental vocabulary the word _quit_ had ever been absent. Wherefore--dizzy, gasping, feebler every minute--he battled fearlessly on in the dying day; never losing his sense of direction, never turning tail, never dreaming of surrender, taking dire wounds, inflicting light ones. There are many forms of dog-fight. Two strange dogs, meeting, will fly at each other because their wild forbears used to do so. Jealous dogs will battle even more fiercely. But the deadliest of all canine conflicts is the "murder-fight." This is a struggle wherein one or both contestants have decided to give no quarter, where the victor will fight on until his antagonist is dead and will then tear his body to pieces. It is a recognized form of canine mania. And it was a murder-fight that Rex was waging, for he had gone quite insane. (This is wholly different, by the way, from "going mad.") Down went Lad, for perhaps the tenth time, and once more--though now with an effort that was all but too much for him--he writhed to his feet, gaining three yards of ground by the move. Rex was upon him with one leap, the frothing and bloody jaws striking for his mangled throat. Lad reared to block the attack. Then suddenly, overbalanced, he crashed backward into the snowdrift. Rex had not reached him, but young Wolf had. Wolf had watched the battle with a growing excitement that at last had broken all bounds. The instinct, which makes a fluff-headed college-boy mix into a scrimmage that is no concern of his, had suddenly possessed Lad's dearly loved son. Now, if this were a fiction yarn, it would be edifying to tell how Wolf sprang to the aid of his grand old sire and how he thereby saved Lad's life. But the shameful truth is that Wolf did nothing of the sort. Rex was his model, the bully he had so long and so enthusiastically imitated. And now Rex was fighting a most entertaining bout, fighting it with a maniac fury that infected his young disciple and made him yearn to share in the glory.