Once, he even barked his demand.
This put the idea into the captain's head, who began immediately to teach him to "speak." At the end of five minutes he had learned to speak softly, and to speak only once--a low, mellow, bell-like bark of a single syllable.

Also, in this first five minutes, he had learned to "sit down," as distinctly different from "lie down"; and that he must sit down whenever he spoke, and that he must speak without jumping or moving from the sitting position, and then must wait until the piece of food was passed to him.
Further, he had added three words to his vocabulary.

For ever after, "speak" would mean to him "speak," and "sit down" would mean "sit down" and would not mean "lie down." The third addition to his vocabulary was "Skipper." That was the name he had heard the mate repeatedly call Captain Van Horn.

And just as Jerry knew that when a human called "Michael," that the call referred to Michael and not to Biddy, or Terrence, or himself, so he knew that _Skipper_ was the name of the two- legged white master of this new floating world.
"That isn't just a dog," was Van Horn's conclusion to the mate.

"There's a sure enough human brain there behind those brown eyes.