He's always watching me," cried Dick in an aggrieved tone.
"Stand still, will you?
Yes, you'd better! You kick, and I'll kick you!" This was to Solomon, who had hitched up his back in an arch, laid down his ears, thrust his head between his fore-legs and his tail between his hind, giving himself the aspect of being about to reach under and bite the tip of the said tail.

But that was not the case, and Dick knew by experience that all this was preparatory to a display of kicking.
Solomon may have understood plain English or he may not.

This is a matter which cannot be decided.

At all events he slowly raised his head and twisted his tail in a peculiar manner, stretched out his neck, and cocking his ears he sighed loudly a sigh like the fag-end of a long bray, all of which seemed to point to the fact that he felt himself to be a slave in leathern chains, gagged with a rusty bit, and at the mercy of his master.
"Flies tease him," said Tom apologetically.

"Poor old Sol!" "Don't touch him!" cried Dick, "or he'll kick you." "Poor old Sol!" said Tom again, and this time he approached the donkey's head.
"Don't touch him, I tell you! He'll bite if you do! He's in a nasty temper because I would put on his bridle, and I was obliged to persuade him to be quiet with a pitchfork handle." "What a shame!" said Tom.
"Shame, eh! Just you look here," cried Dick, and down one of his coarse worsted stockings, he displayed a great bruise on his white leg.