Milk Tissue Variations

the real color of the juice of milkweed, the shape of the cups Avhich hold it. the name of this juice. T^vo Forms of Milk Tissue. Milk tissue may be made up of thick-walled, branching tubes. Milk tissue is often a group of thin-walled, branching tubes. 20 A PRIMER OF BOTANY. Mount for study a stem of Euphorbia. Find the thick-walled tissue of the stem. Speak the name of this tissue. Define the words thiehivalled, thin-walled, and hranching as applied to tissue. All are descriptive of what tissue ? Write in one statement all that is said of milk tissue in the two statements. Mount fur study a stem of lettuce. How is milk tissue formed here?* Are the walls regularly shaped ? Make a statement describing this second form of milk tissue. -- Fill the blanks in the following: (r<) The milk tissue of Euphorbia is (h) The shape of the milk cells is are in outline. and . and , the cells VIII. Thick-walled milk tissue sometimes replaces bast. When latex is eva2:)orated, there is a sticky 7'esidue, Review. 1. Define a plant tissue. 2. When do cells begin to show differences ? sults ? Name four tissues. What re- 3. Give the most abundant tissue. 4. Describe a moss leaf. Locate soft tissue in a stem of geranium. 0. Name the tissue of cocoanut shells. 6. Give three examples of fibrous tissue. Tell its use. * Lead the class to see that it is made by fusion of cells. TISSUES. 21 7. How can bast buiKlles be recognized? 8. Define latex. 9. Give two general forms of milk tissue. 10. Write an example of each. CHAPTER III. TISSUE SYSTEMS. A. WHY EVERY SYSTEM IS MADE UP OF GROUPS. Groups of cells may become a boundary tissue system. Other groups of stony tissue or fibrous tissue draw to- gether as a supporting tissue system. Groups of soft tissue may be pressed into tubes as a conducting tissue system. The plant which Ave see, feel, and enjoy is the result of this division of work among the tissues. -- Tell what is stated about, a boundary tissue system, groups of fibrous tissue, conducting tissue systems. Of what is every tissue system made up ? I. Every tissue system is made up of groups. How does a tissue system form itself? II. Pressure and other conditions of growth cause tissue systems. How many chief tissue systems? -- TISSUE SYSTEMS. 23 -- III. Three, the Boundary, the Supporting-, and the Fundamental Systems. Exercise I. 1. Write three statements about tissue systems. -- Examples. Tissue systems are not found in the lowest pLants. Division into tissues is constantly attempted in plant life, and is accomplished where there is power to match ambition. -- 2. Copy the following : Tissue systems appear as plants become complex. They reach their fullest development in the most com- plex plants. Exercise II. ORAL AND AVKITTEN. -- 1. Use stony tissue, fibrous tissue, and soft tissue in a statement about, the boundary system, the supporting system, the fundamental system. 2. Locate the three tissue systems in, a cross-section of cabbage leaf, a stem of Indian corn. 3. Tell what you think is the nse of each system. Write these 0])inions upon slates or blackboards.* * To avoid mistakes, promote a short conversation about the uses ami names of the tissue systems. 24 A PRIMEK OF BOTANY. THE BOUNDARY SYSTEM. (a) The bouiidaiy system is the simplest tissue system. It is the plant's glove. (Z)) It is the first system discovered in the upward scale of plant life, (c) It is the first to appear in the individual plant. {d) In plants of low type it can scarcely be seen, (e) Examination detects it, in such plants, by its dark, small, and crowded cells. (/) The boundary system of fungi can be lifted from the mass beneath it. ((/) In higlier plants it is sharply separated from other systems. Hair Moss. Name the system of tissues mentioned in every statement. What facts are given in the statements marked (?>), (c), and (f?) ? How is the system told in plants of low type ? In such plants is it developed or in process of formation ? Read the statements marked (/) and (^) ; tell whether the boundary system is developed in fungi. Read (�), and give a reason for the fact. Read the successive statements, and explahi their meaning. Make a statement defining the condition of the boun- If. C. Staff ^""�''WS ; TISSUE SYSTEMS. 25 dary system in the different ranks of plant life make another, stating its office. Since the houndary system of tissues is the first to he developed, it lies 171 a 77iass of thin-walled p7'otoplasm^ ready to he thickened and modified ifito the skin of the pla7it. IV. The boundary tissue system is the simplest and earliest result of plant groAvth. V. It is divided into skin, hairs, and breathing- pores. Test. ORAI.. Club Moss. 1. Give the meaning of the words houndary systeon. -- Caution. Remeinher that all tissues are pushed out from the growing points of plants, and that many circum- stances comhine to press and perfect houndary tissue to he the planfs glove. 2. Examine stems and leaves, and give three qualities of boundary tissue. 3. Tell which cells of the plant become modified in this way. -- 4. What degree of change into boundary tissue is needed in the case of, a mullein leaf ? a blade of grass ? live-forever? fungus ? mildew? water mould ? 26 A PRIMEK OF BOTANY. WRITTEN. 1. Write two statements about the formation of boundary tissue. 2. Write a statement about its position in the plant. 3. Write three statements describing its position in dif- ferent phuits. 4. Write a statement about its use. 5. Write a statement about the boundary tissue of fungus. Fill the blanks, in the following, with words that will -- complete statements about the boundary system : The does not exist in the youngest parts of plants. with their growth. protects the from the . In plants of lower types it is made up of - and cells. Such cells are very like the mass. They readily and for their office as Many low plants have absolutely no The of a rose leaf is a proof of plant develop- ment. The higher the plant, the more thoroughly protective is its . The atmosphere and protoplasm dary tissues. and boun- Write a list of adjectives suitably descriptive of the boundary tissue system.* Thorough Review, with Practice. * The teacher must examine the lists sharply, note errors, and make tliem the basis of a review. TISSUE SYSTEMS. 27 C. MORE ABOUT THE BOUNDARY SYSTEM. The Skin. THINGS TO KEMEMBER. A skill is made of cells modified by (1) cliang-e of form, (2) thickened walls, (3) loss of protoplasm. All these changes may be very slight. Cells may change their form but not thicken their -- walls in, (1) large aquatic plants. (2) land plants living in shade. The cells thicken their Avails without chang-ing shape -- in, (1) land plants which grow very uniformly. (2) plants bred in very dry air. Thickening of cell-walls destroys protoplasm. Skins of plants living in Avater or growing in damp earth retain some protoplasm. 1. Name the outer tissue of a cabbage leaf, and tell of what it is made. Name the tissue of another leaf made of the same. Changes in the form of skin-cells is due to the mode of growth of the plant. If the plant grows alternately tall and broad, the cells 'are extended and flattened. -- 28 A PKIMER OF BOTANY. -- If the growth is mainly in one direction, the cells are not irregular ; as in, grass blades, the leaf of Indian corn, the grains. VI. VII. The true skin is one layer of cells. The outer part of the thickened cell-walls often separates into a continuous, safe wrap around this layer. This wrap is called the cuticle. For various reasons, the skin may split into many layers. This is true of the oleander and cactus. Test I. Make cross-sections of a cabbage leaf, and mount with care. Note the thickened cell-walls. The outer skin upon our bodies is very like the thickened and separable cuticle of the plant. -- Mount and examine the skin uj^on a leaf of, oleander, cactus, holly, mullein, milkweed, verbena, petunia, geranium. Describe the material of the skin of each. Test II. 1. Mention a plant skin that is made of, {a) regular cells. (li) irregular cells. (c) cells full of protoplasm. (d^ thin-walled cells. (e) thick-walled cells. (/) more than one layer of cell tissue. 2. How many of these names are of aquatic plants? TISSUE SYSTEMS. 29 Test III. Write five names of plants near 3^oitr home. Name their tissue system which you see and touch; its parts; its most important part; the composition of this part; decide whether its cells are regular in each plant. Make three statements about (�) a cactus, (/>) geranium, (6^) kelp. What is the boundary system? the skin? Mount a bit of cactus. Treat the cuticle with iodine. It will turn yellow, and can be easily told from true skin. Examine the bloom of fruits and leaves. Mount, and note that it is a waxy matter developed upon the cuticle. HAIRS. -- Mount for examination, hairs of P^""'''^1 ( verbenas. mullein hairs. a root with root-hairs. glandular hairs in different stages of development. VIII. Hairs are extensions of the cells of the true skin. They at first protrude but little. They lengthen, and sometimes become branched. * Hairs secretin^' some substance. 30 A PRIMER OF BOTANY. Hairs are very importa7it upon young roots^ tuJiere they are called root-hairs. Their ivalls are so delicate that they absorb 2^l(^'iit food. Describe each mounted specimen, telling (�) the degree of cell extension, (/>) if the hair is glandular, (c^) whether it is simple or branched. Give, from memor}', three examples of root-hairs; three of variously branched hairs. Think of a reason for the secretion furnished by glandular hairs. Give an especial use of root-hairs. Put upon the blackboard a statement of the material of skin-hairs. Give in two statements, from mounted specimens, the progress of development of glandular hairs. A root-hair is a single cell. -- Place under the slide and describe the appearance of a hair upon, the root of a seedling maple, a root of geranium, a section of beet root, roots of Indian corn. Examine the entire root of an annual, and decide upon tvhat imrt of the root the root-hairs are found. Are the old or fresh root-hairs most absorptive ? -- TISSUE SYSTEMS. SI E. BREATHING-PORES. Our skin lias been called the third lung-, becavise we exhale and absorb by it. This is done by pores upon skin surfaces. The presence of these pores is proved by accidents. If a certain proportion of them is destroyed by burns, scalds, or skin diseases, death re- sults. The plant has breathing- pores, also. They are of im- portance to its life. IX. Breathing-pores are slits in the skin. The slits are guarded by special chlorophyll-stained cells. They are found upon aerial leaves and stems very abundantly; upon underground leaves and stems less abundantly ; and upon true roots never. Mount a cross-section of cabbage leaf. Look for breathingpores. Examine leaves of the, red clover, sunflower, pea, thorn apple, Indian corn, iris. Which surface of the leaf possesses the most breathing- pores ? The lOAver surface. Are there none upon the upper surface ? Breathing--pores are often confined to the lower. cherry, CHAPTER IV. THE SUPPORTING SYSTEM. -- DiEECTiONS. Break a stem of door-yard plantain, and note the tough strings of supporting tissue which run through the soft tissues. The bundles may be readily pulled out. 1. What is found in higher plants? Portions of interior tissue leng-tlien into bundles which penetrate the other tissues. 2. What is the name of these strengthening bundles ? Supporting- tissue. 3. Give its composition. Fibrous and soft tissues. -- Caution. The amount of soft tissue varies^ and there is a7i admixture of less ahunda7it tissues, of doubtful interest to pririiary classes* Test I. Describe the supporting system of the plantain leaf and stalk. * See page 14. 34 A PKIMER OF BOTANY. A. In many ^^Z^wfs, snpporting tissues may be as readily separated as is that of the p)lantain. They are tough and strong^ and divide quickly from more yielding portions of the plant body. B. The leaf determines the supporting tissue^ ivhich is often left as a lace-like framework by beetles^ caterp)iUars^ and many grubs, tvho like the soft chlorophyll tissue which pads and fills out this little skeleton. C. If you will notice about the framework of your hand or your foot, you will see that the leaf and the stem, and the paints of the flower, and the tissites of fruit, are strengthened and held in proper shape by supporting tissue, very much as the systems of tiny bones witJiin your flesh keep your hand a7id foot from being limp and shapeless. -- Use these items in statements about supporting tissue : fibrous tissue, chlorophyll tissue, leaf, stem. Study the bundles of asparagus. Write a statement defining their texture, and their use in the plant body. Study a section of corn stalk, and describe accurately the position of the supporting system of tissues. Note if it be tougher than in asparagus, and give a reason. Examine the framework of a leaf, and tell (1) why the tissue branches so much, (2) why it is so firm and strong, (3) whether soft or fibrous tissue must be more abundant to give this toughness. Give the material of fibrous tissue. -- Look over your written work and tell, (a) the chief materials of supporting tissue. THE SUPPORTING SYSTEM. 35 (b) where supporting tissue is found. ((?) its appearance in a plantain leaf, ((i) what usually pads supporting tissue. (e) where it is found in the plant structure. Test II. 1. Is the supporting system always as plain as in the plantain ? In many plants its limits are vague, and can hardly be told from the inside tissues. 2. Give the material of the supporting system. From the central tissues is pushed a sheath of narrow, long', thin-walled cells. This develops a padding of soft tissue, and outside this padding appears a zone of fibrous tissue. Around all, a layer of starch-bearing cells is packed. This finishes the " bundle." -- 3. Study the stem of red clover, and point out, the jzone of thin-walled cells, the layer of soft tissue. the fibrous tissue, the outside sheath. The young himdles found in the uppe?' joints will be most i7iteresting . Those of the loiver joints will display very much jihrous tissue. 4. Write a statement about the " bundle " of supporting tissue in the stem of ground-pine, or of lycopodium. 36 A PRIMER OF BOTANY. Test III. 1. Name all the parts of a supporting tissue, and tell what part comes next to the boundary system. 2. What do the parts of the supporting system make ? I. The supporting tissues form wood and bark. 3. Turn to the stem of red clover, and statf the position of each part of the supporting system. Do the same with the supporting tissues of plantain. 4. How does the bundle develop ? First, from the simple protoplasm of the growing plant. Second, from the zone of long, thin-walled cells. Third, by the change of such cells into bundle tissues. Sometimes all these cells stiffen into permanent tissue. Such cannot grow further. Why 5. Of what use is this supporting system ? is the material arranged so carefully ? Test IV. BI^ACKBOARD. 1. Select two pupils to write the items of a " bundle." 2. Have the class tell the material of each item, and what they consider is its use. Teach that the laws of the plant's growth pack the tissues according to the needs of the plant body. 3. Receive criticisms and have corrections made. 4. Call attention to the veining of tree leaves, of some plucked-off shrubs, of a leaf of geranium, of a petal. THE SUPPORTING SYSTEM. O/ Have the class tell the material of the veins, and their true name. Kevieiv what a '' bundle " is, where it is found, when, where, and why it is tough and easily drawn from the other systems. -- Blackboard practice in writing statements about, the use of the supporting system of tissues. its position in the plant body. its make-up. its appearance in the plantain stalk. the supporting tissue of a geranium leaf. the supporting system of trees and shrubs. CHAPTER V. THE FUNDAMENTAL SYSTEM. A. MATERIALS. What have you learned about the tissues of a stem ? I. The boundary and supporting tissues guard and shape a stem. Give examples. II. If they are stripped off, fundamental tissue remains. III. In the lowest and simplest plants everything inside -- the skin belongs to the fundamental system ; as, a kelp, rock weed, most mosses. IV. In the stems of large trees there is very little fundamental tissue present. Point out the fundamental tissue in the following, and -- think about what its use must be : a cross-section of pumpkin stem. a section of milkweed. a slice of young wood. How is the fundamental system told in wood? -- THE FUNDAMENTAL SYSTEM. 39 V. The pith of trees, and the rays which run throiig^h wood and bark, are made of the fundaniental system. In wood this system is nearly crowded out by the development of boundary and supporting tissue. (1) Tell of what each of these words is the name, soft, fibrous, stony, milk. (2) Describe soft tissue. (3) Give an example of fibrous tissue. (4) State the condition of walls of stony tissue. (5) Name the colored fluid of milk tissue. In how many forms does fundamental tissue develop? VI. The fundamental system may hold soft, stony, fibrous, and milk tissues. -- Write the names of the tissues found in the fundamental system of, pumpkin, squash, milkweed, apple twig. Exercise. 1. Write the name of the tissue which is most abundant in,-- kelp, cactus, fleshy leaves, fruits. 2. Examine mounted specimens of the above, and state the position of this tissue in the fundamental system of each. 3. Collect five common specimens, and carefully note the amount of soft tissue in comparison with the three others, and where it is found. 40 A PKIMER OF BOTANY. VII. Soft tissue is the most abundant of the fundamental tissues. It is usually the central tissue mass. 1. Look for fibrous tissue masses near tlie skin in tlie -- following : leaves of Scotch pine, ferns. VIII. Fibrous tissue in the fundamental system forms band-like masses, giving strength to the plant form. -- 2. Locate fibrous tissue in the fundamental part of, the leaf of Scotch pine, moss stems, the fern stems, fern leaves, the leaf of a flowering plant. Milk tissue is found in any part of the fundamental system of flowering plants. We see that the tissue masses of the fundamental system are so arranged that the boundary is firm and the interior soft. So ive find that the sin^jlest system can develop ivhat is needed for life. The fibrous and stony tissues lie on the outside of the mass of soft tissue. B. SPACES BETWEEN CELLS. Where are spaces between cells found? Upon leaves, leaf stalks, and stems. THE FUNDAMENTAL SYSTEM. 41 In what leaf surface are tliey usual? In the soft tissue of the under surface. What do they hold? Air and vapor. Where are the spaces large enough to be seen without a glass? In the rushes and Avater lilies. Water Lilies. Examine cross-sections carefully, and state three proper- ties of these large spaces. They are shaped like canals, conduct air, and communicate with the breathing-pores. Where are the spaces found in water plants ? Usually upon the upper surfaces of leaves and leaf stalks. Give a reason. The lower surfaces of leaves which float on the water have few hreathing'-pores. Stalks entirely under water have few pores. 42 A PEIMER OF BOTANY. How are spaces between cells furmed ? By the rapid growth of cells of soft tissue. What is their size and shape in most plants ? Usually small and irregular. What do they mnch resemble? Cells. Where are they largest ? In water plants, the pine tree, and some fruit rinds. What are some intercellular spaces ? Wells of gum. Such sjmces are walled in hy cells making the gum and exudmg it into the cavity. Name a product secreted in this way. Turpentine. -- 1. Study turpentine canals in the large-leaved pines and spruces, and note shape, size, boundaries, character of the boundary cells. -- 2. On which surface of the leaf do they prevail ? 3. Study cross-sections of the leaves of, spearmint, bergamot, sage. Describe the oil receptacles. i. Describe the turpentine canals found in slices of the -- stems of, scrub pine, white pine, balsam fir. THE FUNDAMENTAL SYSTEM. 43 Exercise I. -- Find the spaces between cells in, the soft tissue of pith, the leaf stalk of a water lily. a stem of ivy. Write statements about the size, shape, and contents of the spaces found in each. Cross-sections must be used for mounting. Exercise II. Define the word intercellular. Tell whether the intercellular spaces of this list Section Through Leaf. s. skin. s.f. soft tissue. i.s. spaces between cells. B. bundles. -- are (a) slight or well developed; (6) whether they contain air, or gum, or oil : fresh lemon rind. leaf stalks of water plants. the rind of a fresh orange. the lower surface of an apple leaf. geranium leaves. a leaf of the black currant. meadow grass. a stalk of ice plant. leaves of sundew. stems of the moss rose. -- Make a statement about spaces upon, a leaf of the passion flower, moss rose buds. 44 A PRIMER OF BOTANY. -- c. Fill the blanks in these statements with correctly chosen words : (1) The fragrance of new hay is caused by of meadow grass. in the (2) As the tissues of the grass blades wither, the exudes to the surfaces. (3) The intercellular of pine leaves are and contain . (4) Spaces between the cells of upon upper sides only. plants are found (5) The spaces of ice plants are wells of which looks like ice. (6) The surface of an apple leaf has no , because this surface is without . (7) Study the and lemon. in the fresh rind of the orange (8) Make cross-sections of the of white pine, and study in bark and wood. Review. ORAI.. Read these words: boundary^ supporting^ fundame7ital. Use each of them in connection with plant tissues, and tell how and why tissues divide into systems. Define a tissue system. Where do tissue systems reach the fullest development ? What plants are without them ? Name the three modifications of cells of soft tissue to -- form the boundary system. Define change of form, thickening of walls. disai)})earance of protoplasm. THE FUNDAMENTAL SYSTEM. 45 Account for changes of cell form, and for thickening of cell-walls. Locate skin, hairs, and hreathing-pores in the boundary system of higher phxnts. Is the system separable How in the hnvest plants? separable in higher fungi? Wlieii does protoplasm disappear rapidly in skin-coW^ ? When slowly ? Give examples. How many layers of cells in the shin ? An excep- tion. -- Are the cell-walls of skin tissue thick or thin in, kelp? blights? clover? lily leaves? leaf of holly? Account for the hloom upon a cabbage leaf. What are hairs? Ans. They are absorptive cells piled upon each other. Describe their growth. Tell the most important hairs. What is the use of root-hairs ? Give one example of simple hairs. Of greatly branched hairs. -- What do the hairs of these plants manufacture ? Chinese primrose, petunia, -- Describe breathing-pores upon, verbena. aerial leaves, lower leaf surfaces, submerged stems, a lilac leaf, true roots, lily leaves, red clover, a petal. -- Find the supporting system in, (a) plantain, (5) Indian corn, (e) sweet flag, ((i) red clover, (e) castor-oil plant, (/) brake fern. -- 46 A PRIMER OF BOTAXY. Of what is the supporting system made up? Why is it needed, and how do the tissues draw together to form the "bundle"? What is the fundamental system? Name the four tissues found in it. Tell where in the fundamental system you will find these -- tissue masses : soft tissue, fibrous tissue, stony tissue, milk tissue. Name the composition of a verbena stem, and tell in state- ments the use of each system of tissues. Define intercelhdar. Describe mtercellulai' spaces. Define a turpentine canal. BI.ACKBOAKD. Write, and use correctly in written statements, 1. The names of tissues of plants in the schoolroom. 2. The names of tissues of five plants seen on your way to school. 3. The names of tissue systems in plants at home. 4. The name of a plant which possesses root-hairs. 5. The name of a leaf which has breathing-pores on its lower side only. 6. The name