Part II

of a plant which has no skin. 7. The names of plants possessing supporting systems of tissue. 8. Four words that are tlie names of masses which form the fundamental system. THE FUNDAMENTAL SYSTEM. 47 -- 9. The name of a plant having, a branching hair, a hair which is a gland, very much soft tissue, stony tissue, a tough " bundle," " bloom," a gum reservoir, an oil receptacle. 10. The tissues of plants mentioned in a lesson of your Reader, or in an article of a newspaper, or on a page of a book. ORAL AND BLACKBOARD. Write a definition of protoplasm, and the plant cell. -- Write your idea of a plant tissue. Give, in written statements, (rt) the name of a plant body whose tissues have de- veloped into tissue systems. (5) the name of another, which is a single cell. -- Copy this sentence : " The cells, tissues, and tissue systems are arranged to form the j9/a?i^ body.'^ -- Carefully explain how, (a) cells are pressed into tissues. (5) tissues divide into systems. Give the name of the system which (1) conducts, (2) supports, (3) guards. Of what are all these tissues made ? Where are they lying undeveloped ? Name a plant wholly of naked protoplasm. CHAPTER VI. THE PHYSIOLOGY OF PLANTS. A. WATER IN THE PLANT. -- Directions. " Weigh a handful of green grass ; dry it in an oven. Weigh again : the difference in the two weighings will be very nearly the amount of water in the living plant." 1. Name the living part of every plant. -- 2. Dictate the following for class use : Water is always present in living protoi^lasm ; and the greater its activity, the more ivatery is its composition. A 3. What does the water in protoplasm hokl? proof.* Why 4. is more water required, according to the activ- ity of protoplasm ? Write a statement concerning tissues developed by this activity. 5. Write another statement, naming points in the plant where water is especially needed. The cell-ivalls of living tissues contain much water. 6. At what points of the plant will cell-walls be thus Why saturated? necessarily so? * Plants die without it. THE PHYSIOLOGY OF PLANTS. 49 7. As tissues develop and stiffen into shape, is the water wholly lost ? 8. Prove this by common specimens of flowering })h)nts. Water is so abundant in very simple aquatic * ^j>/cmfs, that ujwn dri/mg tJiem a mere film is left. 9. What percentage of water has a growing land phant? The amount of water in a higher flowering- jilant is seventy-five per cent of its Aveight. The amount of Avater in seaAveeds is often ninety-five per cent. 10. Read the statements of the lesson. Mention the items in each about water in the plant body. Tell which great class of plants contains most water, and why. Why 11. is water so plentiful in active protoplasm ? 1. Write a statement about water in the following plants, -- and give the percentage as lotu or high of water in the plant body : (ct) green slime, kelp. (5) a verbena, grasses. (<?) mosses, ferns. 2. Read the statement, and give very clearly the percent- ages of water. 3. Tell what is found in protoplasm, and what saturates cell-walls. 4. Mention the parts of the plant where watery protoplasm is most abundant. Give a reason. * Explain to the class the meaning of the word aquatic. 50 A PRIMER OF BOTANY. 6. Review the dictated sentences. What have you learned about water in plants? I. All livinj? parts of the plant are abundantly supplied with water. All parts of the plant body, except old wood, are living parts. B. WATER IN PROTOPLASM AND IN CELL-WALLS. Living protoplasm absorbs water for the sake of the food which the water holds. This swells the protoplasm, and is a cause of plant growth. When protoplasm has absorbed all the water it can hold, it continues the process and distils the drops of water within its own boundaries, as reserve matter. The cells of growing tissues display very watery protoplasm. Those of living but sleeping tissues hold thick, -- jelly-like protoplasm ; thus, Put dry beans in soak : the first sign of life is the absorp- tion of water. Seeds are buried iii earth so that they shall absorb the A moisture of the soil. dahlia bulb is soaked^ in order to wake the protoplasm in the tissues. A seed which will not sprout in water has no living proto- plasm. THE PHYSIOLOGY OF PLAXTS. 51 % Water in protoplasmic cells keeps them full and shapely. By this general bracing force soft tissue is kept rigid, and the plant is assisted to its shap)e. Verify the rules by examining with the microscope wellsoaked beans that are beginning to sprout. The absorbed water will be very visible, and its value at the growing point seen in detail. Or, make cross-sections of the tips of the roots of Indian corn, or sections of young asparagus shoots. Examine with the microscope. Stain them with iodine. The protoplasm will turn brow^n. Note the drops of water inside its substance. 1. What is a cell? 2. Of what is green slime made? The oak? The elm ? 3. State the grand point of difference between the slime and elm. Ans. They differ in the number of cells employed, -- 4. What is a cell-wall ? 5. Read carefully this description of its structure : (a) When you look at a slant sunbeam, you see a layer of dust atoms, among ivhich the air appears to be freely p)assi7ig. A (^) cell-wall is a layer of solid particles not in contact, between ivhich the water freely p)asses. (c) Cell-ivalls thicken into formed and p>erfected tissues by the great increase of solid paj'ticles. Solid particles are used-up matters, thus laid on a shelf. -- 52 A PEIMER OF BOTANY. Task. In aquatic plants of low orders the flow of water is continuous from the outside to the inside of their struc- tures. Mount pieces of kelp or fresh-water plauts, and note the wateriness of cell-walls and contents. By the specimens examined, write statements about, (((') the composition of the growing point of a plant, its wateriness, and two reasons for this saturation. (/>) the proof by actual weight of the absorption of water. Its help in supplying the waste by evaporation, (c) the continuity* of water in tissues with that of the soil. The flow in aquatic plants. Describe the real formation of a cell-wall. -- -- Caution. Look over your paper, and see, that all your groups of words are statements, that no word is omitted or misspelled, that the word lyrotoplasm is always correctly used, that you understand what you are expected to know. Varied and persistent practice with specimens. * This word seems the indispensable thing, but had best be explained with an illiistration. THE niYSIOLOGY OF PLANTS. 53 C. DISTURBANCE OF ^YATER IN THE PLANT. II. In winter the water in a plant is motionless, and the plant body rests. During the warm months plants grow, and the water in their structures is disturbed (�) by actual breakage into gases for the plant's use ; (/>) by displacement by solid -- material manufactured in the cell ; (>^) by displacement by liquid matters manufactured in the cell, as, The gradual formation of the tissues which lie undeveloped in the growing points of the plant. III. This work goes on in all cells of all plants, proving that a simple yeast cell is as truly a plant as is a rose tree. If a tiny drop of water is broken up into gases, what is left? Every drop thus broken up leaves a vacancy. How is the vacancy filled ? It is filled, sooner or later, from the flow of water in the cell. Task. Give the reason of the winter rest of plants. Describe the condition of the water in a plant body during the cold months. How is water a plant material ? Give two disturbing agencies in a cell. 54 A PRIMER OF BOTANY. As the drops are used by the cell protoplasm, how are vacancies filled ? From what cells are supplies drawn ? Ans. New supplies of water are drawn from the nearest cells. Caution. In aquatic plants of low orders the needed water is absorbed directly from the surrounding water. Higher aquatic plants possess systems of tissues. In this case the deep-lying tissues must draw their water supply from surrounding cells. Dictate statements concerning water at rest and in motion in,-- (1) an oak. (2) a bit of kelp. (3) a grown geranium. (4) a bean sprout. (5) specimens of green slime or of pond scum. IV. All parts of plants above the g-round or above the water depend entirely upon cell supplies of -- moisture ; as, All the growing cells of the flowering plants and weeds which we have about us in summer. All pad-like leaves that rest upon water surfaces, and all the blossoms of such plants. All aerial (living in the air) roots and rootlets. Give with care, the route of a particle of water from the soil, at the root-hairs of a geranium, to the growing points of the plant body. THE PHYSIOLOGY OF PLANTS. 55 The route of a like particle from the outside to the centre of a well-grown water-lily plant. Examine slime or scum, and describe the absorption of water. D. EVAPORATION. 1. What is a disturbing element in aerial parts of plants ? V. Evaporation of water in the aerial parts of plants -- is a powerful element of disturbance ; as, Expose a cell of pond scum to dry air ; the evaporation is seen hy the collapse of the cell. VI. Evaporation of water in one cell disturbs the water throughout the tissue, and compels it to re-ad- just itself. VII. Dry air and light have influence upon evapora- tion. If the air is full of moisture, the Avater in the plant body cannot exhale, and the cells are distended. When the moisture is blown off by the wind or is dried up by the sun, evapora- tion begins. 2. Note and express in statements the relative rapidity of -- exhalation in the following experiments : Fresh leaves of clover suspended in a tumbler which stands on a wet plate. Other fresh leaves in a dry plate, with no protection from dry air. 56 A PRIMER OF BOTANY. 3. What retards evaporation ? VIIT. The thick outer laj er of skin-cells in the higher plants resists the escape of water. The simple cells of the lowest plants are guarded by very thick walls ; as, tough moulds. Test. WRITTEN. Write the relative rapidity of evaporation in the case of,- the garden plants on a wet day. a cactus. geranium leaves during the night, green slime upon a damp wall, the same placed in warm, dry air. ORAL. � What parts of plants are exposed to evaporation ? How does it disturb the water in the plant? When is this disturbance greatest? Ans. When evaporation is most rapid. How many, and what conditions favor evaporation? What influence has heat? The absorbing power of protoplasm is a "slowing" power about evaporation. Give another reason why plant evaporation seems slow. Ans. Cell water holds many more matters in solu- tion than does pure water, by whose evaporation we are apt to judge it. Why has a cactus a thick skin? In what climates will many layers of skin develop upon a stem ? THE PHYSIOLOGY OF PLANTS. 57 How are plants that are single cells protected ? Define breatliing-pores. Locate them in the boundary system. What do breathing-pores greatly control? Ans. The rapidity of evaporation. How What fills intercellular spaces ? do the spaces com- municate with outside air ? Ans. B}^ the breathing-pores. Is exhalation from the spaces between cells constant? What stops the flow of moist air from these spaces ? Ans. The closure of the breathing-pores. Upon what does the opening and closing of breathing- pores depend? Ans. Upon the surface of the boundary system and upon light. When the plant skin is very dry, they close. E. MOVEMENT OF WATER IN THE PLANT. Why is a movement of the water of the plant unavoid- able? A considerable movement of water supplies the loss by evaporation. (�) In the trees and shrubs we live among-, the movement of water is upward to the leaves. Leaves are losing* water continually. (1) Cut off a tender stem at noon of a dry day ; the leaves wilt at once. 58 A PRIMER OF BOTANY. Place the cut stem in a tumbler of water. Water is greedily absorbed by the stem, and the leaves regain freshness. (2) Tinge with carmine ink the water in the tumbler. Let the stem be delicately thin. In a few minutes the liquid will stain some tissues deeply, and others very slightly. Name the tissues which conduct the fluid easily. (3) Place a leafy apple twig in a bottle of water. Close the mouth with wax to prevent any evaporation from the w^ater surface. The level in the bottle will perceptibly lower, proving the loss by evaporation. (4) Your own experience with a bouquet of cut flowers. (h') The tissue masses through which water usually passes rapidly are those formed of tube-shaped cells of w^oody material. (See cut sjDecimens with the glass.) (c) The movement of the water is through the cellwalls more than through the cells of the tissue masses just described. Solid particles of cellwall attract the water in which they float, and thus, by different displacements, it rises to the top of tall trees. (d} Water moves upward rapidly or otherwise, according to the plant. It has risen nine inches in an hour in a silver poplar. -- THE PHYSIOLOGY OF PLANTS. 59 Bring a little branch of sugar maple i^ito a warm schoolroom. As the branch warms, the sap will flow from the ivomid. Put it out of doors a few minutes, and the flow will decrease ; bi'ing it in again, and the sap will drip as before. This must be done on a cold -- day say zero Fahrenheit or thereabouts. What have you learned about the flow of water (sap) from sugar maples ? (e) The flow of sap from the steins of sug-ar maples seems clue to the influence of heat and cokl upon the tissues of their boundary systems. The water is forced out when it is warm ; at night, when it grows cokl, air is drawn into the stem. When the temperature is much alike through -- the twenty-four hours, that is, in hot weather, -- or in very cold weather, there is no flow of sap. Is there a " circulation of sap " ? (/) There is an upward movement of water, through the warm months, in order to supply the loss from the leaves. There is no dowuAvard movement to correspond. " Circulation of sap " does not exist. Remember, (1) that ivater does not go down into the roots of a tree in the autumn, nor rise in the spring. (2) that there is more icater (sap) in an ordinary tree in winter than there is iyi the spring or the summer. 60 A PRIMER OF BOTANY. (3) that the reason of this abundance is the loss of the leaves, the agents of evaporation. Test I. -- Use these items in a statement : Reason of the movement of water in plants. Direction of the movement. AVrite an example of the route of water up the trunk of a tree. Write the formation of the preferred tissue masses of the route, with a reason why continuous woody cells can draw water drops to the tops of tall trees. Write a statement about the so-called circulation of sap, and mention a popular error about the location of sap in winter. -- Look over the statements written, and tell, (1) why the water must be in motion throughout a growing plant body. (2) why its route is upward. (3) how this may be easil}^ proven. (4) what tissues it prefers for its path. (5) whether there is sap in perennial plants " the year around." -- -- Perennial plants roses, currant shrubs, etc. live -- above ground through the cold months. Annuals like -- the phlox and the pansy die to the ground in early winter. Test II. How would you begin a composition about " The Move- ment of Water in Higher, or Many-Celled Plants"? Think of a proper arrangement of items. -- THE PHYSIOLOGY OF PLANTS. 61 Describe, (^a) a many-celled plant. (6) evaporation. (^) breathing-pores. (cZ) cell-walls. (e) roots. (/) stems. (^) branches. (/i) leaves. Write the composition. Tell whether there is a movement of water in single- celled plants ; if it is considerable. Mention one reason for your decision. CHAPTER VII. MORE ABOUT THE PHYSIOLOGY OF PLANTS. A. PLANT FOOD. What is plant food ? I. Certain g-ases and matters which you will by and by find named and explained in chemistry. Sea Weeds. Some of these matters are essential to our own living; as,-sulphur, iron, and oxygen. With the exception of oxygen, these elements become mixed before the plant uses them. They are usually also mixed with water. No plant can get on without water. : THE PHYSIOLOGY OF PLANTS. 68 -- Caution. Some jolcints live upon the juices of host plants^ as the mistletoe ; manij more live upon decaying matters of the soil, or ujmn decaying animal matter, as the Venus's fly-trap. How is the food eaten ? II. The tissue masses of water plants are so perfectly saturated by the surrounding" water that the food matters which it holds are taken easily into the plant body. III. Leaves of land plants are steeped in the surround- ing air, and take from it g-ases which are plant food. IV. A watery abundance of these foods and all other necessary things to eat are absorbed by the roothairs of land plants. V. The water of the soil holds food materials of all sorts, furnishing them to plants in tiny quantities, and going with them inside the plant body. Test I. BLACKBOARD. Write a statement about plant food, mentioning one food common to the animal and plant worlds. Copy the following names of plants, and use them correctly in statements, locating them as land or water plants pond lily, primrose, toadstools, begonia, plantain, smuts, geranium, grasses, rusts, sundew, cat-tail flag, Jack in the pulpit, duckweeds, ferns, red seaweed, mosses, puff balls, lichens, pitcher plants. 64 A PRIMER OF BOTANY. Decide whether each takes food from (a) surrounding waves, (/>) air and soil water, ((?) other plants, (cZ) dead animals. Rewrite your work, making from it one correct and full statement about each plant. Name the strange plants of the list. -- Caution. The puff halls and toadstools which ive see are fruits. Their |?Za7i^s live underground in any soil full of decaying vegetable matter. Lichens live upon little host p)lo>nts. Write a statement about the food, and habit of eating, of three plants found in your neighborhood. -- Cautions. (1) Do not leave out the item of location ; that is, tvhether they are water or land plants. (2) Name the feiv food materials you hioiv. (3) Ahvays name one food material necessary to plants and animals. Test II. ORAL AND WRITTEN. 1. Tell of what two classes all plants must be. 2. Name all the methods of obtaining plant food. Give the most common methods. Write an example of each. 3. Wliich holds the most plant food, well water or pond water ? -- 4. Dictate the name of a ^^lant, (a) which takes food directly from the water in which it lies, and spends its whole existence. THE PHYSIOLOGY OF PLANTS. 65 (6) which has many leaves spread in the air, a stem with many breathing-pores, and many rootlets pen- etrating the earth. -- 5. Use these items in statements : (�) Blue mould; air; decaying tissue; land plant; old pastry. (5) Ferns ; air ; soil water ; land plant. ((?) Slimes; water; food supply; water plant; oxygen. B. HOW THE FOOD CIRCULATES IN A PLANT. What does the word food mateynal mean ? Do the foods circulate in solid parts or watery parts of plants ? Name two food materials. Name two methods of absorption. Ans. Absorption directly from surrounding air or water, and indirect absorption by diffusion from rootlets. Do aerial parts absorb gases or watery foods? What aerial members of the plant body absorb gases ? How would a perfect state of rest throughout the plant body promote an equal diffusion of food? What aids the diffusion of food matters ? {a) Evaporation greatly aids transportation of food materials by a strong upward movement of water. 66 A PRIMER OF BOTANY. (5) The water drawn upward to the leaves holds in its surfaces the plant foods, and leaves them along its way for the plant's benefit. (c) Plant food can be diffused through plant tissues without any dependence upon evaporation, although it is usually carried along in the water in its upward route. Tell what process aids transporta- tion of plant food. How is movement of the water in the tissue masses promoted by evaporation ? Can diffusion of plant food progress without it ? How ? Ans. By the constant changes of position of the protoplasmic particles composing a growing plant. Exercise I. Sprout three kernels of corn, and transfer them to jars full respectively of distilled water, well water, and -- pond water, and tell, Adder's Tongue Fern. (a) whether the plants grow in all the jars. (6) what very important food is in all the jars. (c) in which jar the plant does best. (c?) how the food materials are scattered through the plant body in each jar, and what process aids the diffusion. THE PHYSIOLOGY OF PLANTS. 67 What hinders an equal diffusion of food throughout the plant tissues ? Ans. Chemical changes that happen as soon as food touches tissue hinder an equal diffusion of food matters. Exercise II. 1. Try a simple experiment with plant foods, and state results from plant growth. 2. Write a reason why pond or river water is a tonic for plant life. 3. Name a food material absorbed from the air. 4. Mention one reason for the unequal transportation of most foods among tissue masses. Ans. Unequal extensions of the plant body by growth. 5. Write in statements a description of internal changes, with the reason why they are inevitable in a certain order of plants. Name the order. Ans. The higher order. Exercise III. (Just before the hour is up.) Correct all mistakes made in Exercise II. Place the correct statements on the blackboard. G8 A PRIMER OF BOTANY. c. STARCH. 1. By what is food material used? -- Food material is used hy the protoplasm^ and generally at once ; tlius^ Water is at once made use of. 2. What has to be done with the food for the green parts of plants ? It has to be broken up and tvorked over inside the plant body. 3. What is the new food material called ? It is starch; and the working over is called starch-making. Starch-making goes on in chlorophyll grains in all the green parts of plants. 4. Oil^ instead of starchy is manufactured in the chlorophyll grains of certain plants. 5. Spell and define chlorophyll^ chlorophyll grain. What is necessary for starch-making? Sunlight and chlorop>hyll masses are necessary for starchmaking. Parts of 2^1ants devoid of chlorophyll make no starchy and chlorophyll masses are unable to manu- facture starch in darhiess. What is done during the dark hours? -- -- The new food material that is, starch is digested^ and transported to all jxirts of the plant body. THE PHYSIOLOGY OF PLANTS. 69 Starch is changed during digestion to liquid matters^ in order that it may thus rise very easily in the tissues, f Ca7ie sugar is one of the watery onus of starch. How Foods are Stored. Write a statement about the potato. How is a potato filled with starch ? The potato leaves make starch in sunlight. In the night starch is changed to a liquid food^ and is sent throughout the ijlant stems. In the underground stem (potato) the liquid food turns to starch again. Why is starch stored in the potato ? Describe a starch cupboard that is not an underground cell. Tell what the castor bean stores. Why is any sort of food material reserved in stems or seeds ? What will they sometimes feed? At what time will they be needed? -- Name and describe the making of an important food stored by, (a) the artichoke, with particular mention of the points of the plant where the material is first manufactured, and of a change which takes place afterwards to aid diffusion. (J) kernels of green corn. Taste them, and name the material which tastes sweet. Is this starch or liquid food? (c) a mustard seed ; tell a use of the plant food stored in it, and why the seed is a good