And it had stuck, shudderingly, in his uncannily sensitive memory.

Yet now, he himself had just had a like experience.
In an instant, the pup's trustful friendliness was gone.

The man had come on the Place, at dead of night, and had struck him.

That must be paid for! Never would the pup forget,--his agonizing lesson that night intruders are not to be trusted or even to be tolerated.

Within a single second, he had graduated from a little friend of all the world, into a vigilant watchdog.
With a snarl, he dropped the bag and whizzed forward at his assailant.
Needle-sharp milk-teeth bared, head low, ruff abristle, friendly soft eyes as ferocious as a wolf's, he charged.
There had been scarce a breathing-space between the second report of the pistol and the collie's counterattack.