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HISTOLOGY OF MEDICINAL PLANTS
HISTOLOGY OF MEDICINAL PLANTS
BY WILLIAM MANSFIELD, A.M., Phar.D. Professor of Histology and Pharmacognosy, College of Pharmacy of the City of New York Columbia University TOTAL ISSUE, FOUR THOUSAND NEW YORK JOHN WILEY & SONS, Inc. London : CHAPMAN & HALL, Limited Copyright, 1916, by WILLIAM MANSFIELD...
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PREFACE
PREFACE
The object of the book is to provide a practical scientific course in vegetable histology for the use of teachers and students in schools and colleges. The medicinal plants are studied in great detail because they constitute one of the most important groups of economic plants. The cells found in these plants are typical of the cells occurring in the vegetable kingdom; therefore the book should prove a valuable text-book for all students of histology. The book contains much that is new. In Part I
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CHAPTER I THE SIMPLE MICROSCOPES
CHAPTER I THE SIMPLE MICROSCOPES
The construction and use of the simple microscope (magnifiers) undoubtedly date back to very early times. There is sufficient evidence to prove that spheres of glass were used as burning spheres and as magnifiers by people antedating the Greeks and Romans. The simple microscopes of to-day have a very wide range of application and a corresponding variation in structure and in appearance. Simple microscopes are used daily in classifying and studying crude drugs, testing linen and other cloth, repa
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CHAPTER II COMPOUND MICROSCOPES
CHAPTER II COMPOUND MICROSCOPES
The compound microscope has undergone wonderful changes since 1667, the days of Robert Hooke. When we consider the crude construction and the limitations of Robert Hooke’s microscope, we marvel at the structural perfection and the unlimited possibilities of the modern instrument. The advancement made in most sciences has followed the gradual perfection of this instrument. The illustration of Robert Hooke’s microscope (Fig. 7) will convey to the mind more eloquently than words the crudeness of th
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CHAPTER III MICROSCOPIC MEASUREMENTS
CHAPTER III MICROSCOPIC MEASUREMENTS
In making critical examinations of powdered drugs, it is frequently necessary to measure the elements under observation, particularly in the case of starches and crystals. Microscopic measurements are made by the ocular micrometer (Fig. 21). This consists of a circular piece of transparent glass on the centre of which is etched a one- or two-millimeter scale divided into one hundred or two hundred divisions respectively. The value of each line is determined by standardizing with a stage micromet
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CHAPTER IV HOW TO USE THE MICROSCOPE
CHAPTER IV HOW TO USE THE MICROSCOPE
In beginning work with the compound microscope, place the base of the microscope opposite your right shoulder, if you are right-handed; or opposite your left shoulder, if you are left-handed. Incline the body so that the ocular is on a level with your eye, if necessary; but if not, work with the body of the microscope in an erect position. In viewing the specimen, keep both eyes open. Use one eye for observation and the other for sketching. In this way it will not be necessary to remove the obse
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CHAPTER V REAGENTS
CHAPTER V REAGENTS
Little attention is given in the present work to micro-chemical reactions for the reason that their value has been much overrated in the past. A few reagents will be found useful, however, and these few are given, as well as their special use. They are as follows: Distilled Water is used in the alcohol, glycerine, and water mixture as a general mounting medium. It is used when warm as a test for inulin and it is used in preparing various reagents. Glycerine is used in preparing the alcohol, glyc
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CHAPTER VI HOW TO MOUNT SPECIMENS
CHAPTER VI HOW TO MOUNT SPECIMENS
The method of procedure in mounting specimens for study varies according to the nature of the specimen, its preliminary treatment, and the character of the mount to be made. As to duration, mounts are either temporary or permanent. In preparing a temporary mount , place the specimen in the centre of a clean slide and add two or more drops of the temporary mounting medium, which may be water, or a mixture of equal parts of alcohol, glycerine, and water, or some micro-chemical reagent, as weak Lug
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CHAPTER I THE CELL
CHAPTER I THE CELL
The cell is the unit of structure of all plants. In fact the cell is the plant in many of the lower forms—so called unicellular plants. All plants, then, consist of one or more cells. While cells vary greatly in size, form, color, contents, and function, still in certain respects their structure is identical. The typical vegetable cell is composed of a living portion or protoplast and an external covering, or wall . The protoplast includes everything within the wall. It is made up of a number of
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CHAPTER II THE EPIDERMIS AND PERIDERM
CHAPTER II THE EPIDERMIS AND PERIDERM
The epidermis and its modifications, the hypodermis and the periderm, form the dermal or protective outer layer or layers of the plant. The epidermis of most leaves, stems of herbs, seeds, fruits, floral organs, and young woody stems consists of a single layer of cells which form an impervious outer covering, with the exception of the stoma. The cells of the epidermis vary in size, in thickness of the side and end walls, in form, in arrangement, in character of outgrowths, in the nature of the s
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CHAPTER III MECHANICAL TISSUES
CHAPTER III MECHANICAL TISSUES
The mechanical tissues of the plant form the framework around which the plant body is built up. These tissues are constructed and placed in such a manner in the different organs of the plant as to meet the mechanical needs of the organ. Many underground stems and roots which are subjected to radial pressure have the hypodermal and endodermal cells arranged in the form of a non-compressible cylinder. Such an arrangement is seen in sarsaparilla root (Plate 38, Fig. 4). The mechanical tissue of the
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CHAPTER IV ABSORPTION TISSUE
CHAPTER IV ABSORPTION TISSUE
Most plants obtain the greater part of their food, first, from the soil in the form of a watery solution, and, secondly, from the air in the form of a diffusible gas. In a few cases all food material is obtained from the air, as in the case of epiphytic plants. In such plants, the aerial roots have a modified outer layer—velamen—which functions as a water-absorbing and gas-condensing tissue. Many xerophytic plants absorb water through the trichomes of the leaf. Such absorption tissue enables the
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CHAPTER V CONDUCTING TISSUE
CHAPTER V CONDUCTING TISSUE
All cells of which the primary or secondary function is that of conduction are included under conducting tissue. It will be understood how important the conducting tissue is when the enormous quantity of water absorbed by a plant during a growing season is considered. It will then be realized that the conducting system must be highly developed in order to transport this water from one organ to another, and, in fact, to all the cells of the plant. Special attention must be given to the occurrence
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CHAPTER VI AERATING TISSUE
CHAPTER VI AERATING TISSUE
The aerating tissue of the plant performs a threefold function: first, it permits the exchange of gases during photosynthesis; secondly, it permits the entrance of oxygen and the exit of carbon dioxide during respiration; and, thirdly, it permits the exit of the excess of water absorbed by the plant. The above functions are carried on by the stomata, the water-pores, the lenticels, and the intercellular spaces of the plant. The stoma functions as the chief channel for the passage of CO₂-laden ai
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CHAPTER VII SYNTHETIC TISSUE
CHAPTER VII SYNTHETIC TISSUE
Under synthetic tissue are grouped all tissues and cells which form substances or compounds other than protoplasm. Such compounds are stored either in special cavities or in the cells of the plant, as the glandular hairs; internal secreting cavities of barks, stems, leaves, fruits, seeds, and flowers; photosynthetic cells or cells with chlorophyll, and the parenchymatic cells which form starch, sugar, fats, alkaloids, etc. The most important non-glandular synthetic tissue is the photosynthetic t
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CHAPTER VIII STORAGE TISSUE
CHAPTER VIII STORAGE TISSUE
Most drug plants contain storage products because they are collected at a period of the year when the plant is storing, or has stored, reserve products. These products are stored in a number of characteristic ways and in different types of tissue. The most important of the different types of storage tissue that occurs in plants are the storage cells, the storage cavities, and the storage walls. Several different types of cells function as storage tissue. These cells, which are given in the order
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CHAPTER I ROOTS AND RHIZOMES
CHAPTER I ROOTS AND RHIZOMES
Some fifty-five roots, rhizomes, and rhizomes and roots are official in the pharmacopœia and national formulary. About 5 of these are obtained from monocotyledonous plants, and 50 from dicotyledonous plants. In studying the structure of roots and rhizomes, then, it must first be determined whether the root in question is monocotyledonous or dicotyledonous. This fact is ascertained by determining the type of the fibro-vascular bundle. The bundle is of the open collateral type in all rhizomes and
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CHAPTER II STEMS
CHAPTER II STEMS
When studying stems it should first be determined whether they were derived from monocotyledonous or dicotyledonous plants. This fact is ascertained by determining the type of the fibro-vascular bundle. See Chapter XI. The next fact to determine is whether the stem is from an herb or from a woody plant. This fact is readily determined because herbaceous stems have a true epidermis, masses of collenchyma at the angles of the stem. The cortical cells contain chlorophyll, and the pith is very large
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CHAPTER III WOODY STEMS
CHAPTER III WOODY STEMS
The cross-section of a buchu stem (Plate C), 1.6 millimeters in diameter, shows a few of the epidermal cells modified into thick-walled, roughish, unicellular trichomes (1). The remaining epidermal cells have a thick, wavy outer wall (2). Beneath the epidermis are several rows of cortical parenchyma cells (3) which extend to the bast bundles and in which are found the secretory cavities with the thin-walled secretory cells (4). The bast fibres (5) occur in continuous bands, varying greatly in si
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CHAPTER IV BARKS
CHAPTER IV BARKS
Barks are all obtained from dicotyledonous plants. In studying barks there should be ascertained the thickness, arrangement, form, structure, color, and cell contents of the cells occurring in the outer , middle , and inner barks. The outer bark includes the cork cells and the phellogen layer. The middle bark includes all the cells occurring between the phellogen layer and the beginning of the medullary rays. The inner bark includes the medullary ray cells and all cells associated with them. The
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CHAPTER V WOODS
CHAPTER V WOODS
Quite a number of drugs consist of the wood of woody plants; such drugs are quassia, red saunders, white sandalwood, and guaiac. When studying woods it is necessary to observe the cross, tangential, and radial sections. Such sections of quassia are shown in Plates 105, 106, and 107. When studying these sections it should be remembered that while the types of cells forming quassia wood are similar to the cells forming other woods, still their structure, arrangement, and amount will vary in a reco
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CHAPTER VI LEAVES
CHAPTER VI LEAVES
Leaves collectively constitute the greatest manufacturing plant in the world. Most of the food, clothing, and medicine used by man is formed as a result of the work of the leaf. The cell contents, structure, and arrangement of the different cells of the leaf differ in a marked degree from the cell contents, structure, and arrangement of the cells in the other organs of the plant. This accounts for the presence of the large amount of chlorophyll in the leaf, the presence of stomata, and the pecul
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CHAPTER VII FLOWERS
CHAPTER VII FLOWERS
The histological structure of flowers is readily seen in the powder; therefore, in studying flowers, it is not necessary to section the various parts. Each part of the flower should be isolated and powdered separately and each separated part studied. In each case the powders will contain surface, cross-, and radial sections of the parts powdered. While studying flowers, special attention should be given to the pollen grains, to the papillæ of the petals, to the papillæ of the stigma, and, in cer
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CHAPTER VIII FRUITS
CHAPTER VIII FRUITS
There is great variation in the structure of fruits, such a variation, in fact, that no one fruit has a structure typical of all the other fruits. Each fruit, however, has a pericarp and one or more seeds. The amount and structure of the cells forming the pericarp and the seeds of fruits differ in different fruits, but for each fruit there is a normal amount of, and a characteristic, cellular structure. Nearly all the important medicinal fruits are cremocarps or umbelliferous fruits. The plan of
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CHAPTER IX SEEDS
CHAPTER IX SEEDS
Seeds are very variable in structure, so much so, in fact, that scarcely any two seeds have a similar structure. It is necessary, therefore, when examining seeds, to compare the structure of the seed under examination with authentic plates or with the section of a genuine seed. The layers of the seed are the spermoderm, perisperm, endosperm, and embryo. In some seeds the spermoderm forms the greater part of the seed; in others the perisperm is greatest in amount; in still others the cotyledons m
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CHAPTER X ARRANGEMENT OF VASCULAR BUNDLES
CHAPTER X ARRANGEMENT OF VASCULAR BUNDLES
Having familiarized ourselves with the different types of mechanical and conducting cells, we shall now consider the different ways in which these cells are associated to form the vascular and fibro-vascular bundles . The simplest form of the vascular bundle occurs in petals, floral bracts, and leaves. In these parts the vascular bundle is made up of conducting cells only. In the great majority of cases, however, the conducting cells are associated with mechanical cells to form the fibro-vascula
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