movement. The circumnutation of plants gives them an aptness for those special movements which may result from the influence of light and gravity. We shall see hereafter that the spontaneous movements of children give them aptness for the production of those series of movements which express the action of mind. inherited. Aptness to certain conditions is often inherited, that Aptness is to say, is due to impressions produced upon the ancestors. Children who inherit a tendency to Myopia develope it more easily during school days than do others. A tendency to certain tricks or habits has often been observed to be transmitted by inheritance. Charles Darwin has recorded many such examples. In such cases the tendency or aptness is inherited, though the condition itself may not be produced. Having studied examples of growth for the purpose Logic. of aiding our descriptions of man, we pass on to some considerations as to the logic of common descriptions of phenomena in living things; this remark specially concerns speaking of the causes of what we see in Nature. In the descriptions of action in the brain which I shall have to give, the endeavour will be made, not to speak of cause and effect, but of the necessary antecedence and sequence of what we see; and it must always be remembered that the sequence of a phenomenon can never be a part of its causation. It is doubtless true that logic should guide our observations and arguments, but, in some cases, observation, especially as to the time of events, may help to correct our logic. It has been said that the daisy opens to meet the Antecedent and sequent rising sun. Observation shews that light must act upon not to be the flower before it opens: light, not a desire in the conflower to greet the sun, is the necessary antecedent to the movement. If you assume that something resident founded. The child as we see him. living things. in the flower opens its petals, and if you observe the flower open before the sun illuminates it, then the logic of the statement made above may be correct. It seems that in other cases the assumption of an "It" resident in a living thing may help to put the logic right. This seems to me to be the case in some examples of mental action, as we shall see hereafter. Now coming to the child, as a work of Nature, we have to describe the child as we see him, without making any assumptions, except that the same forces regulate action in his body as in other living things. In this Lecture we study works of Nature at the two extremes of the scale. The modes of Nature's work may be best learnt among the simple vegetable organisms, and the generalisations formed may aid our understanding of action in man. Let us now look at a boy, he is a living thing, he moves, and it is at once obvious that his actions are controlled by sight and sound, as he first follows a butterfly in the attempt to catch it, then comes back when you call him. Look at him-what about his brain, does it act more like a potato or a turnip? most resembles a potato, for soon you will be satisfied that its separate parts can act independently of one another. It Observing When we observe a living thing in contrast to an inorganic body, we soon find the importance of deciding as to what separate parts of the object can act more or less independently. Action of any kind, whether growth or motion, can only be observed by our senses in some material part. It does not, however, follow that the object chosen for observation consists of only one part, one and indivisible. Having determined the parts to observe, note the action in each part, i.e. its time, quantity and kind. Then note the sequence or outcome of the action of each part, and of the series of actions in the whole subject. If you accept the views given as to the forces aiding Character and controlling the attributes and characters of the acts formed by surroundof growth and action, it may appear to you probable ing influ that the child trained under certain surrounding in- ences. fluences will be impressed by them, and formed by them, and will subsequently grow in harmony with them; the surroundings largely make the character of the child. It seems to be true that when certain forces have long acted upon a living thing, and have altered its modes of growth or modes of action, that the said living thing remains impressionable to that same force or set of forces. This is in part what is meant when it is said that faculty is increased by use or exercise. In applying such principles it must be remembered that there are internal forces affecting the child's growth and action, but these intrinsic forces, which result from antecedent impressions, may be modified by the environment. In the next Lecture we shall give particular attention to the study of brain-centres and look at modes of action in them, similar to those seen in lower living things. The brain is one of the most complex organs in the body, we know that it consists of parts which can be stimulated to separate action. We want to study how the brain acts, and in such inquiry our preliminary survey of Nature will help us. CHAPTER II. STUDY OF THE BRAIN AS A PART OF THE BODY. observa tion. We now have to study the brain as a part of the body, and determine, as best we may, its modes of action. In the first lecture we observed certain vegetable specimens, which were selected for their simplicity, and we found that it was often possible and convenient Widening to divide the subject observed into parts, which can act and conindependently of one another as to time of action, or tracting the field of unequally as to quantity of action. In so doing we contracted, or limited the field of observation and thought; thus we considered action in individual groups of cells in the radicle of the pea. At other times we found reason to enlarge our field of observation, action in one subject could not be understood by looking at it alone; we understood the flower of the iris better when observing two flowers and a bee. So in now proceeding to study the brain, we begin by dividing it into parts called nerve-centres, which it has been shewn can act separately or in different ratios under varying circum Two flowers and a bee. Nerve centres and stances. Having studied nerve-centres as to their properties, the brain. we shall again enlarge our field of observation, including the whole brain, the organs of special sense, and the muscular system which is the mechanism for the expression of thought and action. cells. The brain is a soft and delicate structure, seated in the brain case and carefully protected; it consists essentially of two kinds of material, the nerve-cells, and the nerve-fibres. The nerve-cells, when duly nourished, are Nervethe makers of nerve-force; for their proper nutrition they need a good supply of blood in their vessels. A nerve- Nervefibre passes off from each cell and conveys the force fibres. generated in it, which is then called a nerve-current; Nervethere are millions of such cells in the structure of the current. brain. When the nerve-force generated by a nerve-cell is carried by a fibre to a muscle, say in the face, or in the limbs, this nerve-current causes the muscle to contract or shorten, and visible movement results, the movement being stimulated by the force sent from the nervecell. The movement seen indicates to us the time and Nervemuscular quantity of the discharge of force from the nerve-cell ; movement. such movement is conveniently called a nerve-muscular movement. The substance of the brain is thus mainly made up The brain. of groups of nerve-cells, many of which are connected with one another by nerve-fibres, and many of them are connected with the muscles of the body and send nervecurrents to them, thus causing the movements of the members. The nerve-cell generates force as the outcome of its nutrition. While the brain is giving out force, it must be replenished by nutrition, or it will run down, and be less capable of producing energy after a short time, it will then need food and rest. We have spoken of the nerve-cells of the brain as Afferent nerve being connected with one another, and with the muscles fibres. |