PART III
Histology of Roots, Rhizomes, Stems, Barks, Woods, Flowers, Fruits and Seeds
CHAPTER I
roots and rhizomes
Cross-section of pink root 219
Cross-section of ruellia root 219
Cross-section of spigelia rhizome 223
Cross-section of ruellia rhizome 226
Powdered pink root 227
Powdered ruellia root 227
X CONTENTS
CHAPTER II
STEMS
PAGE
Herbaceous stems 233
Cross-section, spigelia stem 233
Ruellia stem 235
Powdered horehound 237
Powdered spurious horehound 237
Insect flower stems 241
CHAPTER III
WOODY STEMS
Buchu stem 242
Mature buchu stem 242
Powdered buchu stem 245
CHAPTER IV
BARKS
White pine bark 248
Powdered white pine bark 250
CHAPTER V
WOODS
Cross-section quassia 254
Radial-section quassia 254
Tangential-section quassia 258
CHAPTER VI
LEAVES
Klip buchu 260
Powdered klip buchu 262
Mountain laurel 264
Trailing arbutus 264
CHAPTER VH
FLOWERS
Pollen grains 270
Non-spiny- walled pollen grains 273
Spiny-walled pollen grains 273
Stigma papillae 274
CONTENTS XI
PAGE
Powdered insect flowers 278
Open insect flowers 280
Powdered white daisies 282
CHAPTER VIII
FRUITS
Celery fruit 285
CHAPTER IX
SEEDS
Sweet almonds 289
CHAPTER X
ARRANGEMENT OF VASCULAR BUNDLES
Types of fibro- vascular bundles 292
Radial vascular bundles 292
Concentric vascular bundles 295
Collateral vascular bundles 295
Bi-collateral vascular bundles 298
Open collateral vascular bundles 298
Part I
SIMPLE AND COMPOUND MICROSCOPES AND MICROSCOPIC TECH NIC
CHAPTER I
THE SIMPLE MICROSCOPES
The construction and use of the simple microscope (magni- fiers) 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, repairing watches, in reading, and identifying insects. The more complex simple microscopes are used in the dissection and classification of flowers.
The watchmaker's loupe, the linen tester, the reading glass, the engraver's lens, and the simplest folding magnifiers consist of a double convex lens. Such a lens produces an erect, en- larged image of the object viewed when the lens is placed so that the object is within its focal distance. The focal distance of a lens varies according to the curvature of the lens. The greater the curvature, the shorter the focal distance and the greater the magnification.
The more complicated simple microscope consists of two or more lenses. The double and triple magnifiers consist of two and three lenses respectively.
When an object is viewed through three lenses, the magnifi- cation is greater than when viewed through one or two lenses, but a smaller part of the object is magnified.
3
HISTOLOGY OF MEDICINAL PLANTS
FORMS OF SIMPLE MICROSCOPES
TRIPOD MAGNtFIER
The tripod magnifier (Fig. i) is a simple lens mounted on a. mechanical stand. The tripod is placed over the object and the focus is obtained by means of a screw which raises or lowf the lens, according to the degree it is magnified
watchmaker's LOtJPE
The watchmaker's loupe (Ftg. 3) is a one-lens magiufi< mounted on an elwny or metallic tapering rim, which can be
Tic. I.— Tripod Magnifier
placed over the eye and held Iracting the eyelid,
Fro. 2. — Watchmaker's Loupe I position by frowfting or cob-
folding MAGNIFIER
The folding magnifier (Fig. 1) of one or more lenses is mounted in such a way that, when not in use, the lenses fold up like the
Fig. 3, — Folding Magnifii-r Fig. 4. — Reading Glas;
blade of a knife, and when so folded are effectively protected from abrasion by the upper and lower surfaces of the folder.
READING GLASSES
Reading glasses (Fig. 4) are large simple magnifiers, often
six inches in diameter. The lens is encircled with a metal band
and pro'ided with a handle.
1
n a. uid
fiecH be^
I I
THE SIMPLE MICROSCOPES
STEINHEIL APLANATIC LENSES
Steinheil aplanadc lenses (Fig. 5) consist of three or four lenses cemented together. The combination is such that the field is large, fiat, and achromatic. These lenses are suitable
Fig. 5,— Sfeinheil Apl;
for field, dissecting, and pocket use. When such lenses are 1 in simple holders, they make good dissecting microscopes.
DISSECTING MICROSCOPE
The dissecting microscope (Fig. 6) consists of a Steinheil leos and an elaborate stand, a firm base, a pillar, a rack and
Disscetinij Mic;ri>acupt-
6 HISTOLOGY OF MEDiaNAL PLANTS
pinion, a glass stage, beneath which there is a groove for holding a metal plate with one black and one white surface. The nature of the object under observation determines whether a plate is used. When the plate is used and when the object is studied by reflected light it is sometimes desirable to use the black and sometimes the white surface. The mirror, which has a concave and a plain surface, is used to reflect the light on the glass stage when the object is studied by transmitted light. The dissecting microscope magnifies objects up to twenty diameters, or twenty times their real size.