In an action of trespass for a personal assault, if the defendant justifies under the plea of son assault demesne, he must show that the plaintiff committed the first assault, and that what was thereupon done by him, was in *278the necessary defence of his own person. G-reenl. Ev., s. 95. And he must also show that the force used by him was appropriate in kind, and suitable in degree. Commonwealth v. Clark, 2 Met. R., 23.

The instructions given in this case are in accordance with these principles.

Exceptions overruled.