In addition to the automatic functions, there is a second great class of processes which are also managed from the third level; that is, by the discharge of nervous energy from particular parts of the spinal cord. These are the so-called Reflex functions. 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. Furthermore, each of the senses has its own set of reflex adjustments to the stimulations which come to it. The eye accommodates itself in the most delicate way to the intensity of the light, the distance of the object, the degree of elevation, and the angular displacement of what one looks at. The taking of food into the mouth sets up all sorts of reflex movements which do not cease until the food is safely lodged in the stomach, and so on through a series of physiological adaptations which are simply marvellous in their variety and extent. These processes belong to the third level; and it may surprise the uninitiated to know that not only is the mind quite "out of it" so far as these functions are concerned, but that the brain proper is "out of it" also. Most of these reflexes not only go on when the brain is removed from the skull, but it is an interesting detail that they are generally exaggerated under these conditions. This shows that while the third or lowest level does its own work, it is yet in a sense under the weight--what physiologists call the inhibiting action--of the higher brain masses. It is not allowed to magnify its part too much, nor to work out of its proper time and measure. The nervous apparatus involved in these "third-level" functions may be called the "reflex circuit" (see Fig. 2), the path being from the sense organ up to the centre by a "sensory" nerve, and then out by a "motor" nerve to the muscle. [Illustration: FIG. 2.--_s c mt_ = reflex circuit; _s c sp mp c mt_ = voluntary circuit.]