smooth plaster. The floor should be of hard wood and "caulked" like the deck of a ship, or covered with some impervious material, so that it may be sluiced with water or disinfecting fluid and rapidly dried. The ordinary method of warming by one or more open fireplaces is, on the whole, perhaps the best; closed stoves, hot-air and hot-water coils are often disagreeable and difficult to manage. But whatever system be adopted, it must be remembered that the object to be attained is to keep the whole body of the air in the room at as regular a temperature as possible. VENTILATION. The question of ventilation is closely connected with that of warming, since in all ordinary systems the difference in density of air at different temperatures is relied upon to provide the motive force. Efficient ventilation is of the highest importance not only for maintaining the general good health and comfort of the occupants of the schoolroom, but also as a direct means of preventing the spread of infection when imported. The object to be aimed at is a complete and uniform exchange of the air in the room with that outside, and as this must be effected without creating draughts or unduly lowering the temperature of the air in the room, it will be readily understood that this is a problem not easily solved. Many systems of ventilation have been devised of a more or less complicated nature, but speaking generally, the more simple the apparatus, if adapted to the requirements of the room, the better are likely to be the results. Respired air leaves the lungs at a temperature but little below that of the normal body temperature, viz., 98.2° F., and so is, as a rule, warmer than the general mass of the air in the room, and its density is in consequence less; it therefore ascends towards the top of the room, and if there are proper outlets there, it will escape and be replaced by.colder air from outside. Moreover, the air in the room will, as a general rule, be maintained at a higher temperature than that outside by the heating apparatus, and this will further facilitate the exchange. For the admission of air from the outside proper inlets must be provided, otherwise the incoming air will not be properly diffused, and draughts will be created. Therefore the essential features of a system of natural ventilation are a properly regulated system of air outlets near the top of the room and a similar system of air inlets around the lower part. It is found in practice that the most suitable temperature for the air in the schoolroom is from 60° to 65° F., but in summer the temperature of the outside air sometimes rises as high or higher than this, and the circulation of the air in the room will then become very sluggish, and some additional means must be sought to promote it. This may be done by opening the windows and making use of the ordinary atmospheric movement to remove the air of the room by perflation or by connecting the air outlets. with an upcast shaft in which an upward current of air can be maintained by a gas jet or a small furnace. This latter is sometimes called the method of ventilation by extraction. On the other hand, when the temperature of the outside air is low, the velocity of the current through the air inlets may be so great as to cause draughts, and lower the temperature of the air in the room. Other practical difficulties have also to be provided for. Where the room is warmed by open fireplaces there will be a strong upcast current of air from the fire through the chimney, and if not provided against, the cool air from the inlets may simply sweep along the lower part of the room to the fireplaces and escape by the chimneys without replacing the respired air in the upper parts of the room. This difficulty is sometimes overcome by placing separate air inlets below and behind the fireplaces. Again, in certain conditions of the outside atmosphere, such as wind or moisture and density, the pressure upon the air outlets may be such as to check the outward current of air or even reverse it, entirely disarranging the system of circulation. To obviate this many elaborate contrivances have been devised, but the simpler such extraction cowls are the better they are likely to act and the less liable to get disarranged. The ventilation of the schoolroom should always be independent and self-contained; that is to say, the supply of incoming air should not be derived through doors from passages or other rooms, but through proper openings constructed for the purpose. The outside openings of such inlets should be placed some little distance from the ground in situations where the air is not liable to be contaminated by sewer gas or other impurities. They should be protected in some way against the entrance of dust and the direct pressure of the wind, and some means of temporarily closing them may be desirable. The internal openings of the inlets should be placed at intervals around the room at a height of four or five feet from the floor, and the incoming current of air should be broken by a gauze screen or other device. The air passages may pass directly through the walls, or it may be necessary to conduct the air some distance in an air tunnel. This should be easily accessible for cleaning purposes. To ensure that the incoming air shall be properly diffused the total area of the air inlets should be sufficiently large. Ventilation by perflation is only permissible when the temperature of the outside air is such as to allow of a comfortable existence in the open air. This can only be said to be the case when the shade temperature rises above 65° F. In such circumstances, where there are plenty of windows to open, this method is sometimes comfortable and efficient, as the air in the room becomes practically continuous with that outside. In prac tice windows are largely made use of as a means of ventilation both as air inlets and as air outlets; but a schoolroom should not depend upon its windows for its ventilation, as it is almost impossible to regulate the currents of air satisfactorily by such means. The air outlets should be placed around the upper parts of the room, whence they may pass through the walls to the outer air, or in the ceiling, whence the ascending currents may be conveyed to the roof by one or more upcast shafts. Where artificial lights are used they may advantageously be placed below the air outlets, so as to ensure a sufficient velocity in the ascending current of air to overcome the outside pressure and to carry off the products of combustion. To ensure this velocity also, the total area of the outlets should be somewhat smaller than that of the air inlets, but these areas must be proportionate to each other and to the size of the room. The total amount of air passing through the room will depend upon these factors. Another air outlet which is often made use of is an opening at the upper part of the room into the chimney, but this often spoils the draught of the chimney and allows the smoke of the fire to escape into the room. The frequency with which the air in the room will require to be changed to ensure efficient ventilation will depend upon the number of its occupants, the length of time it is occupied, the number of fires and lights and other circumstances, and widely differing figures have been set down by different authorities, but speaking generally, while maintaining the temperature of the room not below 60° F., and avoiding draughts, the more frequently the air in the room is changed the less will be the chance of the air which has been respired by one individual, and which may contain infective organisms, being respired by another and so communicating infection. A good practical test of the efficiency of the ventilation of a room is that on entering it from the outer air after it has been occupied an hour or more, no sense of closeness or stuffiness should be perceptible. One or more thermometers should be placed in the room remote from the fireplaces to indicate the temperature. Ingress to and egress from the schoolroom should be by doors opening outwards into a lobby or lobbies. These should always have good cross ventilation independent of that of the schoolroom, and may be fitted with hat and coat rails, and lockers, so that hats, overcoats and books which are not immediately required may be left there, and not brought into the schoolroom. The latter also should only be occupied during school hours, and not used for dinners and other such purposes. The Object of Ventilation.-The object of ventilation is to prevent the accumulation of organic impurities and any deficiency of oxygen, such as may arise from burning gas in a room for purposes of illumination. Since the organic matter does not admit of direct estimation, the percentage of carbonic acid in the air is usually taken as an indirect measure of its amount, and this is at the same time a measure of the deficiency of oxygen. Air which has been fouled by breathing is injurious if it contains more than 95 per cent. of carbonic acid. Knowing the amount of air passed through the lungs in one hour and the amount of carbonic acid it contains, calculation easily shows that if the percentage of carbonic acid is to be kept down to the limit of 05 per cent., a man should live in a room whose capacity is not less than 28,000 litres (1,000 cubic feet), and into which at least 60,000 litres (2,000 cubic feet) of fresh air are admitted each hour.-Huxley's "Elementary Physiology," p. 168. No. 26, VOL. 3.] A COURSE OF ELEMENTARY AND EXPERIMENTAL PLANT-PHYSIOLOGY. (Communicated by Prof. L. C. Miall, F.R.S.) HE course was arranged in the first instance for junior agricultural students, with little or no scientific knowledge. The time available was five hours a week, divided into sections of two hours, one hour, and two hours, on three consecutive days. The course extended over twenty weeks (October-March), but included other natural history subjects, being intended as an introduction to a general course of agricultural study. The want of summer sunlight was found to be a serious difficulty. Microscopes and the usual appliances of a biological laboratory were at command. A similar course would be useful in the higher forms of a secondary school, in a rural technical school, in some higher-grade schools, and in other places where the conditions are similar to those described above. We have endeavoured, as far as possible, to give to the course the form of an inquiry. To rouse curiosity, to satisfy curiosity by the results of personal observation and experiment, never, if we can help it, to give the information beforehand, to make the answer to one question suggest a second question-these are the methods of teaching by inquiry, and it will be seen how widely they differ from the lecturing system, which, by whatever name it may be called, is almost universal in the science courses of to-day. We are aware that we have not always, nor with due thoroughness, carried out the intention of making every lesson and every part of a lesson an inquiry. But the intention has never been out of our minds, and with greater knowledge, experience, and ingenuity, we could have realised it more fully. Our successors cannot fail to improve upon this attempt if they will aim at the same end. It has been a matter of serious consideration how full a syllabus to lay before the teacher. If it is scanty, he complains that he is left to solve many difficulties unaided; if it is full, he loses initiative and liberty. We have thought it best. to work out the first section of the course with some fulness as a sample of the method, and to treat the rest more concisely. The course (of which this is only an instalment) was drawn up by Professor Percy Groom, of Cooper's Hill; Professor M. C. Potter, of Newcastle; Mr. Harold Wager, Inspector of Science and Art Schools; and the following members of the staff of the Yorkshire College, viz., Professor Miall, Dr. W. G. Smith, Mr. T. H. Taylor, and Mr. N. Walker. I.-CARBON-FIXATION. (1) Let us begin with an object lesson on leaves. Freshgathered leaves of various kinds, evergreen and deciduous, simple and divided, living and fallen, thin and succulent, leaves of one-seed-leaved and two-seed-leaved plants, will be F required, and there should be enough to give one of each kind to each student. Questions: What is there common to the form of nearly all leaves, however they may differ in detail? Any exceptions to the broad and flat form? In what circumstances are thick leaves formed? What does the broad and thin form suggest as to the probable functions of a leaf? That it exposes a larger surface to the light; that it gives out something to the air, or takes in something from the air. If the time of year is suitable, make naked-eye observations on the scars of fallen leaves. Some discussion of the use of special kinds of leaves will interest the class. Holly, oak, ash, wheat or any other common grass, heather, crowberry or other rolled leaves, are examples, but the discussion cannot be pushed far while the students possess no special knowledge. A point may be made here and there, but much will be left unexplained for the present. This first lesson is to suggest, not to satisfy. Consider, together with the class, how they can learn for themselves something about the chief functions of leaves and the way in which those functions are discharged. Lead them to feel that they must get some knowledge of leaf-structure before they can attack questions of leaf-function. (2) Ask for suggestions from the class as to the best ways of studying the structure of a leaf. Failing anything better, the following will prove useful. Examine box-leaves, fresh or alcohol-preserved, which have been boiled in 5% caustic potash for 15 minutes. The epidermis can easily be detached. Mount it in water on a glass-slip, and draw it by the microscope. Remove the lower epidermis in the same way. Draw. Examine the mesophyll and leaf-veins which remain when the upper and lower epidermis have been removed. Draw the veins. (3) Tear off the lower epidermis from a fresh leaf of elder, or, in winter, from a leaf of Linaria cymbalaria (toad-flax), which is common as a greenhouse weed. Mount in water and observe the stomates; their parts, the colour of the guard-cells, the distribution of the stomates. Draw. (4) Suggest that it would be instructive to see the parts of a leaf not in detached layers, but from top to bottom in one view. Difficulty of opacity-how it can be got over? Make the leaf transparent? This will answer with very thin leaves, e.g., of young fern. Make them transparent by the same process as that employed in the case of the box-leaf. But a thick leaf cannot be studied in this way—why? The method of thin sections may be suggested. Show small groups of students how to cut sections. Let each cut and mount in water a section of laurel leaf (preserved in alcohol). (5) Show the class how to mount in balsam thin sections of laurel leaf previously cut and stained with hematoxylin. Draw. (6) See what has been learned about leaf-structure. Run over the epidermis, how the epidermal cells differ from those of the mesophyll, where stomates are to be found, the palisade cells, the looser cells which lie between the palisade cells and the lower epidermis, the spaces between them (what do these spaces contain ?) (7) Try to find an answer to the question at the end of 6. Take a kettleful of water which has been just boiled, and distribute it in warmed tumblers to the class. A fresh laurel leaf is then dipped in a tumbler of hot water. Air is seen to pass out, from the lower surface only, in small bubbles. Cut a tolerably thick section of a fresh leaf, mount in water with a cover-glass, and examine by the microscope. The confused appearance of the mesophyll, and especially of its lower part, will lead to some perplexity, if the students are unfamiliar with the look of irregular air-bubbles. Run in some alcohol. The air is quickly driven out in the form of spherical bubbles. We show in this way that the irregular, intercellular spaces contained air. How did the air get in? By examination of good sections it can be made out that the stomates lead into the air spaces. Where do the air spaces lead? Show, by blowing into water, through a buttercup leaf, that they lead a long way into the plant. Blow through the leaf in both directions. (8) Find open stomates in a bit of fresh epidermis mounted in water (3). Run in some 2.5% solution of common salt. Observe the closing of the stomates. What was the action of the salt solution? The teacher may make this clear by the well-known plasmolysis experiment (Bower's "Practical Botany for Beginners," II., ii., iii.). The salt solution abstracts water from the guard cells, and then the stomate closes. Add water to the epidermis; the guard cells, as they absorb the water, swell, and the stomate opens. (9) Make a model to show the action of the water in opening a stomate. Take a piece of rubber-tubing, close one end, and secure it to an upright board; bend the tube into a close loop, whose two limbs touch all along; secure the bends of the loop by strips of card fastened to the boards with drawing pins ; pass a pin or two between the limbs of the loop, to prevent both bending in the same direction to right or left. Now connect the open end of the tube with an oxygen bottle. On admitting the gas, the two limbs, which were in contact, diverge, and leave an oval opening between. Thus we see how elongate cells, which lie side by side, and whose ends are fixed, separate from one another when distended. (10) Notice the contents of the mesophyll cells of a fresh leaf-section. See the green corpuscles scattered through them, and remark that the green colour is confined to the corpuscles. See the green corpuscles in a living leaf of a water-moss, or other transparent green plant. (11) What is the green colouring-matter? We give it a name (chlorophyll), but that does not let us into any important secret. No one can as yet tell us anything that signifies about the nature of the chlorophyll, but we can easily learn how to recognise it, and we may come to know that it is a substance of great value to the living plant. One step towards a knowledge of chlorophyll is to learn how to separate it from the plant-tissues. Is it soluble in water? Try the action of water upon leaves, leafsections, &c. No result. Try hot water. No result. Try alcohol. The tissues lose their colour, and the alcohol turns green. (12) To get a good supply of chlorophyll solution, boil some grass leaves, chopped small, and pour alcohol on them. When the alcohol is deeply tinged, filter it into a flask. Notice that the liquid is green by transmitted, reddish by reflected light. (13) A good way to recognise certain coloured liquids is to get their spectra. Show how to get a spectrum of didymium, &c., by the lantern and a prism. Show in the same way the spectrum of hæmoglobin and chlorophyll. Get the same spectra by means of a spectroscope; the spectrum of chlorophyll is not indispensable to what follows, but the demonstration is interesting and instructive. Let the students put the parts in working order after they have been deranged, learn where to place the lens, how to get the best width of slit, &c. We have used a number of technical terms, but if they present any difficulty, plain English words can be found. We might call the epidermis the skin, the mesophyll the inner tissue, the stomates pores, chlorophyll leaf-green. In lessons to children or uneducated persons the Latin and Greek would be quite out of place, and even grown-up people, who have received much instruction, sometimes become enslaved by their vocabulary, so that it is well sometimes to talk plain English, even to them. (14) We want to get the class to make acquaintance with the chief properties of starch, which are involved in any investiga tion of the uses of chlorophyll. How shall we bring it in? They will never think of it for themselves. We may bring it in without a word of preface in the form of a practical problem. The teacher does not always keep to one route, nor always pass by easy steps from the known to the unknown. He sometimes deviates for the sake of variety and surprise. We bring into class some pale, nearly colourless leaves (tropæolum, primrose, sunflower and marigold answer well), preserved in a large bottle of alcohol, put one of the leaves into a dish, and pour sherry-coloured iodine-solution upon it, naming the solution as we do so. In two or three minutes the word "solarised" can be read upon the leaf. Ask how the word came there. The name of iodine solution will put some of the class on the track. Iodine turns starch blue, and no doubt there was starch (perhaps painted on the leaf?) where we now see the word solarised. Show that the letters do not rub off, and when the right moment comes explain that you cut these letters out of a card (produce the card), and fixed the card upon a living leaf in broad sunshine. Wherever the sunlight fell, starch now appears in the leaf, and that starch can be made visible any number of times by bringing the leaf out of alcohol and putting it in iodine solution. (15) Show the change of colour when iodine solution is poured upon dry starch, and thin starch paste. One part of starch to 200 times its weight of boiling water is strong enough. Try the same test upon a slice of potato, a piece of bread, a slice of onion-bulb, a slice of crocus-corm, a turnip, an apple, &c. (16) To show starch under more natural conditions, cut thin sections of a potato tuber, stain by adding a drop of Bismarck brown solution to the section; wash off after one minute with 70% alcohol; add a drop of iodine solution; cover, examine and draw. (17) Remark the white colour of a mass of starch. Many other vegetable substances are white or whitish (paper, wood, &c.). The white proves nothing at all as to composition. Wood and paper, for instance, are largely made up of black carbon. Char them, and the black colour shows at once. How can we prove that charcoal contains carbon ? Heat strongly with air in a sealed test-tube of glass (not too soft), connected with a bent tube, which can be passed into limewater. Heat the charcoal till it glows, without warming the air in the tube more than can be helped. Then warm the upper part of the tube, and drive the gas into the lime-water (Smithells in "Object Lessons from Nature"). Repeat with starch; the same results will be got. (18) Where does the starch come from? It is not supplied to the plant ready-made. (How do we know this?) It is made by the plant. Since starch contains much carbon, carbon in some form must be supplied. Does the plant get its carbon from the ground? We shall not be able to say without further inquiry, but if the question were put again a little later, it could be answered. Does the plant get its carbon from the air? Animals, burning wood and coal, &c., send much carbon dioxide into the air; can plants make use of that source of carbon ? Provide six wide-mouthed bottles, washed out with water, to keep the air within moist; into 1 and 2 put living green leaves; into 3 a green leaf killed by boiling; into 4 roots, a piece of fungus, a piece of living wood, and any other living plant tissue which is not green. Leave 5 empty for the moment; it it is to serve as a check. Into 6 put a living leaf. Charge all the bottles with about an equal quantity of CO from the mouth; cork, and seal with vaseline. Place bottles I, 3 and 4 in a good light,' 2 in the dark. After 24 hours test all 1 The experiments can be carried out successfully with winter sunlight. the bottles except 6 for CO, with lime-water.' Note the results, and draw conclusions. (19) Into bottle 6 we have put a living green leaf. Pass a twice-bent tube through the cork and let the outer limb dip into a coloured liquid contained in a small beaker. Cause the liquid to rise a little way in the tube. Charge the air in the bottle with CO, as before; seal, and expose to strong light, not sunlight. Mark the level of the liquid in the tube when all the preparations are complete. Test the bottle for CO after 24 hours, and observe before disturbing anything whether the level has altered. What is learned from this experiment? We are now in a position to show : (1) that living green plants absorb CO, from the air in (2) that they do not absorb CO2 in the dark; (4) that not-green parts of living plants do not absorb CO,; (20) What gas can this be? Place a piece of living Elodea (the Anacharis of our ditches) in water, and expose to sunlight. Observe the train of bubbles issuing from the cut end. Collect the gas from a large quantity of Elodea placed beneath an inverted funnel, and exposed to bright sunshine. Determine that it consists largely of oxygen by alkaline pyrogallic acid solution, or other method." (21) Expose a thin, green leaf which has been kept in the dark for at least 24 hours to sunlight, darkening one part with tin-foil. Tropaeolum is good, but many others answer well. Kill with boiling water, decolorise with alcohol, place in iodine solution, and observe that starch has formed wherever the sunlight got access. This experiment can be varied in a number of ways. (22) Expose a variegated leaf (Pelargonium answers well) in the same way. (23) Expose a leaf as before, but exclude CO, by potash solution. (24) Expose half of a leaf to air containing CO,, the other half (which is not to be detached) to air devoid of CO,. Sunlight as before. (25) Expose leaf of a land-plant as before to sunlight and CO2, but keep the leaf covered with water. (26) Repeat the last experiment with a leaf which is ordinarily submerged, such as a Potamogeton (pond-weed). (27) Rub the under-side of a leaf cautiously with vaseline, to block up the stomates. Expose as before. (28) Place the leaf in a saucer kept cold by ice. Expose as before. (29) Summarise the results of Sections 18-28. You are now able to prove that green leaves can form starch independent of roots. (30) Our experiments show indirectly that starch formed in a leaf during sunlight disappears in the dark. Try this expressly. What becomes of the starch? Starch is insoluble in water(proof?) imperfectly soluble in boiling water. Is there any known method of dissolving it without utter destruction? Action of human saliva (instructions in Foster and Langley's "Practical Physiology," Lesson XV.). Try the action of malt 1 Also test the bottles with lime-water before the experiment is entered upon. If they have been washed out with hard water, the lime-water may turn milky in every case. 2 Inequalities of temperature rapidly affect the level of the water in the tube. A check experiment (bottle and tube without a leaf), and bell jars to keep off currents of air, will be useful precautions. The temperatures should be noted. 3 Professor Smithells suggests the following method :-" The oxygen in the tube may be absorbed by thrusting up into it a bundle or brush of fine copper wire, and then introducing, by means of a bent pipette, a quantity of strong ammonia solution. The oxygen is absorbed in about half-anhour, and a blue solution of the ammoniacal copper compound is formed. There will probably be an unabsorbable residue of nitrogen in the tube." extract on starch paste. Prove by Fehling's test or phenylhydrazin that sugar is formed in each case. (31) Is there any substance in a living green leaf which can change starch into sugar? Take leaves of pea, tropæolum, &c., gathered in evening or night; bruise them, extract with a small quantity of cold water, and test the properties of the extract on thin starch paste, starch grains in the field of the microscope, &c. (32) Gather leaves of the pea (Pisum sativum) at night; dry at 40°-50°C; powder finely. The watery extract may be tried at any time afterwards on starch grains or starch paste; it is even more energetic than the extract from fresh leaves. (33) If time and the knowledge of the students allow, it may be shown that in the dark sugar accumulates in the neighbourhood of the leaf-veins (Detmer, " Pflanzen-physiologie," par. 115, Engl. trans., par. 115). (34) Again summarise the results obtained : Starch is formed in living leaves of certain plants (1) in sunlight, (2) when chlorophyll is present, (3) when CO, is present, (4) when the stomates are open (land-plants), and (5) when the temperature is suitable. If any one of these conditions is not satisfied, the formation of starch may be hindered altogether. Starch may form in a leaf which is separated from the root and stem. Starch and nearly all parts of a plant contain carbon. The source of the carbon? The source of the oxygen exhaled by the plant in sunlight ? Starch is convertible into a soluble substance, which can be transported to distant parts of the plant. The use of the starch in bread suggests that starch may be useful as food to the plant and its various organs. Make it plain that the parts played by chlorophyll and sunlight in the formation of starch are still uninvestigated by us ; we know nothing more than that their co-operation is essential. (35) Elicit from observations on greenhouses, bell-jars containing plants, &c., that wherever plants are enclosed by glass, moisture is apt to collect on the glass. Where does the moisture come from? Some comes from the damp earth; possibly all. Test this supposition by experiments. Take a flower-pot with a living plant in it, cover the earth and pot with indiarubber sheeting, fitted close to the stem to prevent the escape of water vapour; cover it with a bell-glass, and see whether the glass is bedewed. Put the covered pot (without the bell-jar) on the scale of a balance, counterpoise it, and see whether there is any gain or loss in an hour or a day. [By more elaborate methods (see Darwin and Acton) the loss of water can be more exactly measured.] (36) Does the water escape with equal facility from both surfaces of the leaf? This may be tested by laying strips of paper previously dipped in a strong solution of cobalt chloride' upon laurel leaves, some of which have the upper and some the lower surface exposed. Show beforehand that the blue paper turns pink when moistened, and that the change of colour is quicker and more decided when the supply of moisture is greater. Press a fresh leaf between two plates of glass, and notice which plate is most bedewed. (37) What channels exist by which moisture can possibly ascend from the ground or a vessel of water to the leaves? Cut off a leaf of Pelargonium with a razor, and dip the cut end of the leaf stalk into a strong watery solution of eosin. The path of the coloured solution can soon be made out ; it becomes very distinct in time. Follow up the inquiry by examining the vessels in boiled rhubarb, &c. 1 Stahl recommends a 1% solution for delicate investigations, and a 5°c solution for demonstration purposes. Reasons have been now discovered for concluding that green leaves are carbon-fixing and also transpiring organs. Take care not to let it be inferred that they are nothing else. In the course of their future work the students may discover that leaves discharge other functions of equal importance with these. PSYCHOLOGY AND SCIENCE By PRINCIPAL LLOYD MORGAN, F.R.S. It is said that not long ago a praiseworthy pupil thus briefly indicated the rôle of a lecturer on psychology :-" He tells us what everyone knows in language which nobody can understand." If I presently fall under this indictment it will not be from lack of warning. And if, notwithstanding my best efforts to avoid psychological platitudes, I speak of matters which are already familiar to science teachers, how, I venture to ask, could it be otherwise? Psychology being a study of the laws of mental sequence, it is impossible for a teacher faithfully to exercise his calling without reaching conclusions of practical value with regard to the linkage of intellectual ideas. Since it is the establishment of certain modes of sequence in the accumulating experience of the pupil which it is his business, as teacher, to secure, must he not, if honest in purpose, have given this matter some thought? It is indeed conceivable that a scientific investigator should, so to speak, take his mental faculties and the manner of their operation for granted, and rest content with the results which they somehow produce. But even he, as exposi tor of these results, must consider -one could wish that in many cases he considered to better purpose-how best to set them forth so as to establish a due sequence in the minds of his hearers or readers. He is, in fact, so far a teacher-one who has to weigh not only the facts in themselves, but how they are to be fitly presented; and since they are to be presented to another mind, he must have some knowledge of the way such facts affect such a mind. But for the teacher by profession the effects of the manner and method of presentment are of primary importance. Furthermore, in giving to the world the results of his researches, the man of science may say: "Here are my observations and conclusions clearly and systematically set forth. If from want of training or through lack of mental grasp you cannot assimilate them, that is no concern of mine." The science teacher, however, may not urge such an excuse for failure, since for him observation and conclusions are to be regarded as a means to the end of education. It is easier to indicate what is not education than to give a satisfactory definition which shall summarise what it is. Paraphrasing a well-known description of metaphysics, we may all agree that when one fellow talks about what he doesn't understand to other fellows who don't understand him, that's-not education. We shall all agree, too, that such a proceeding is quite unknown where science teaching is concerned! It may smuggle candidates as contraband goods through the custom house of the examination hall; but it is assuredly neither science nor teaching as we understand these words. I will, however, venture to ask this question. If the science teacher does not understand the workings of the mind which he is endeavouring to train, does he not so far fall short of the ideal we should all set before us? Is he very different from the doctor who prescribes without an adequate knowledge of the 1 An Address delivered at the Conference of Science Teachers at the Southwestern Polytechnic, Chelsea, on January 11th, 1901. |
