organs, not only within the traditional five, but also within the muscles, tendons, joints, and internal organs of the body such as the heart, and digestive organs. In all these places we find ends of neurones which converge at the spinal cord and travel to the brain. They are called sensory neurones and their function is to carry messages inward to the brain. Thus, the brain represents, in great part, a central receiving station for impressions from the outside world. The nerve-cells carrying messages from the various parts of the body terminate in particular areas. Thus an area in the back part of the brain receives messages from the eyes; another area near the top of the brain receives messages from the skin. These areas are quite clearly marked out and may be studied in detail by means of the accompanying diagram.

There is another large group of nervecells which, when traced out, are found to have one terminal in the brain and the

other in the muscles throughout the body. The area in the brain, where these neurones emerge, is near the top of the brain in the area marked Motor on the diagram. From here the fibers travel down through the spinal cord and out to the muscles. The nerve-cells in this group are called motor

neurones and their function is to carry messages from the brain out to the muscles, for a muscle ordinarily does not act without a nervous current to set it off.

So far we have seen that the brain has the two functions of receiving impressions from the sense-organs and of sending out

orders to the muscles. There is a further mechanism that must now be described. When messages are received in the sensory areas, it is necessary that there be some means within the brain of transmitting them over to the motor area so that they may be acted upon. Such an arrangement is provided by another group of nerve-cells in the brain, having as their function the transmission of the nervous current from one area to another. They are called association neurones and transmit the nervous current from sensory areas to motor areas or from one sensory area to another. For example, suppose you see a brick falling from above and you dodge quickly back. The neural action accompanying this occurrence consists of an impression upon the nerve-cells in the eye, the conduction of the nervous current back to the visual area of the brain, the transmission of the current over association neurones to the motor area, then its transmission over the motor neurones,

down the spinal cord, to the muscles that enable you to dodge the missile. The association neurones have the further function of connecting one sensory area in the brain with another. For example, when you see, smell, taste and touch an orange, the corresponding areas in the brain act in conjunction and are associated by means of the association neurones connecting them. The association neurones play a large part in the securing and organizing of knowledge. They are very important in study, for all learning consists in building up associations.

From the foregoing description we see that the nervous system consists merely of a mechanism for the reception and transmission of incoming messages and their transformation into outgoing messages which produce movement. The brain is the center where such transformations are made, being a sort of central switchboard which permits the sense-organs to come into communication with muscles. It is

also the instrument by means of which the impressions from the various senses can be united and experience can be unified. The brain serves further as the medium whereby impressions once made can be retained. That is, it is the great organ of memory. Hence we see that it is to this organ we must look for the performance of the activities necessary to study. Everything that enters it produces some modification within it. Education consists in a process of undergoing a selected group of experiences of such a nature as to leave beneficial results in the brain. By means of the changes made there, the individual is able better to adjust himself to new situations. For when the individual enters the world, he is not prepared to meet many situations; only a few of the neural connections are made and he is able to perform only a meagre number of simple acts, such as breathing, crying, digestion. The pathways for complex acts, such as speaking English or French, or