It was speech to Jerry, full of unmistakable meaning.
As the shake grew rougher, Jerry emitted his most ferocious growl, which grew more ferocious with the increasing violence of the shaking.

But that, too, was play, a making believe to hurt the one he liked too well to hurt.

He strained and tugged at the grip, trying to twist his jowl in the slack of skin so as to reach a bite.
When Skipper, with a quick thrust, released him and shoved him clear, he came back, all teeth and growl, to be again caught and shaken.

The play continued, with rising excitement to Jerry.

Once, too quick for Skipper, he caught his hand between teeth; but he did not bring them together.
They pressed lovingly, denting the skin, but there was no bite in them.
The play grew rougher, and Jerry lost himself in the play.