They include all those responses which the nervous system makes to stimulations from the outside, in which the mind has no alternative or control.

They happen whether or no.

For example, when an object comes near the eye the lid flies to reflexly.

If a tap be made upon the knee while one sits with the legs crossed the foot flies up reflexly.

Various reflexes may be brought out in a sleeper by slight stimulations to this or that region of his body.