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LABORATORY AND FIELD
MANUAL OF BOTANY



BY



JOSEPH Y. BERGEN, A.M.

Author of " Elements of Botany," " Foundations of Botany,
" Primer of Darwinism," etc. '



AND

BRADLEY M. DAVIS, Ph.D.

Professob of Botany in the University of Pknnsvt >v axta



GINN AND COMPANY

BOSTON • NEW YORK • CHICAGO • LONDON
ATLANTA • DALLAS • COLUMBUS • SAN FRANCLSCO



Copyright, 1907, by
(Joseph Y. Bergkn and Bradley M. Davis



ALL RIGHTS RESERVED
716.10



CINN A.\n COMl'AXV • PRO-
PRIETORS • ROS TON • U.S.A.



PREFACE



This manual offers material for much more than a year's
laboratory work. This is made necessary by the fact that in-
structors differ widely in their views as to what matter should
be presented in an introductory course under the variety of
conditions obtaining where botany is taught. • A course must
necessarily be framed selectively, and the chief alternatives are
discussed in the opening paragraphs of the Introduction.

The authors fully recognize the fact that no set of directions
of only moderate fullness can tell the student all that he needs
to know aboult choice of material, apparatus, and manipulation.
It is assumed that much is left to be explained by the instructor,
and constant mention is made of general and special laboratory
guides which may be consulted for needed details.

The student in the laboratory is not to consider himself as
merely the corroborator of facts already ascertained : he is to
interrogate mainly not the instructor, not the manual, but the
plant itself. The directions here given are, therefore, for the
most part suggestions on methods of procedure and indications
as to the plants or parts of plants in which to look for desired
information.

Since the amount of ground that can be covered by labora-
tory divisions varies so largely with many circumstances, it has
seemed desirable to designate two courses, a briefer and a fuller
one. The matter which may be omitted from the latter to frame
the shorter course is printed in smaller type and consists in the
main of rather more difficult or detailed studies than those which
appear in the larger type. In a general way the order of treat-
ment follows that of the authors' Principles of Botany ^ but the



iv PREFACE

sliorter course does not cover many more topics than are dealt
with in Bergen's Elements or Foundations of Botany, and may be
used with either of those books.

Part I consists mainly of studies on the gross anatomy and
tlie histology of seed plants, together with a set of separately
numbered experiments to illustrate some of the main principles
of plant physiology.

Part II deals Avith type studies of spore plants, outlining the
evolution and classification of the plant kingdom. Here will also
be found studies on the gametophyte phases and the life histories
of seed plants to show their relationships to the spore plants.
Part II is introduced by outlines on the plant cell to illustrate
the chief principles of growth and reproduction.

Part III is concerned with a series of laboratory and field
studies which may serve to offer at least an outline for the
treatment of ecology as a scientific subject. Profound ecological
studies demand far more knowledge of taxonomy, plant phys-
iology, meteorology, the physics and chemistry of soils, and
kindred subjects than can be required of beginners in botany.
However, the authors believe that it is quite possible to illustrate,
even to beginners, something of the kind of quantitative discus-
sion of variations in environment and the responses of plants
to changed conditions, which must distinguish the ecology of
the future.

Hearty acknowledgments for valuable suggestions are due to
A. T. Bell, F. E. Clements, W. N. Olute, W. F. Ganong, B. Gruen-
berg. Miss Lillian J. MacRae, G. J. Peirce, and R. B. Wylie, who
liave wholly or in part read the manuscript or the proofs.

J. Y. B.

('AMHKiiKiE, March, 1907 ^ ^i j)



CONTENTS



INTRODUCTION

LABORATORY METHODS AND EQUIPMENT



Page
1



PART I — STRUCTURE AND PHYSIOLOGY OF SEED PLANTS

Introductory Study of a Seed Plant and its Organs . . . ,15

The Seed and its Germination 17

Storage of Food in the Seed 21

Movements, Development, and Morphology of the Seedling . . .27

Roots 29

Some Properties of Cells and their Functions in the Root . . . oG

Stems 87

Structure of the Stem 30

Work of the Stem 45

Buds 48

Leaves 51

Leaf Arrangement with Reference to Light 53

Minute Structure and Functions of Leaves 55

The Flower of the Higher Seed Plants 64

Pollination and Fertilization 68

The Fruit 69



PART II — TYPE STUDIES PRECEDED BY THE STUDY
OF THE PLANT CELL



The Plant Cell, its Structure and Reproduction

The Flagellates, or Flagellata

The Sliuie Molds, or Myxomycetes

The Blue-Green Alg«, or Cyanophycese

The Green Alg?e, or Chlorophycese

The Brown Algffi, or Phgeophyceae .

The Red Algse, or Rhodophyceaj .

The Bacteria, or Schizomycetes

The Yeasts, or Saccharomycetes .

The Alga-like Fungi, or P'hyco'myceres



75

83

83

84

87

97

100

102

105

107



VI



CONTENTS

Page

The Sac Fungi, or Ascomycetcs HO

The Lichens 112

The Basidia Fungi, or Basidiomycetes 114

The Liverworts, or Ilepatica; H"

The Mosses, or Musci 126

The Ferns, or Filicinese 132

The Horsetails, or Equisetinese 142

The Club Mosses, or Lycopodineae 145

The Gymnosperms, or Gymnospermce 151

The Angiosperms, or Angiospermse 159



PART III — ECOLOGY



Parasitic and Carnivorous Plants .
How Plants protect themselves from Animals
Pollination of Flowers ....
How Plants are scattered and propagated
Competition and Invasion

Plant Successions

Ecological Classes

Plant Formations ; Zonation .
Study of Types of Seed Plants



167

168
168
172
174
175
175
177
179



BOTANICAL MICROTECHNIQUE

General Reagents employed in Temporary Preparations . . . 188
Some Special Reagents for Microchemical Tests and Temporary Prepa-
rations ............ 190

Killing and Fixing ........... 191

The Preservation of Material 195

General Staining Methods 197

Mounting in Balsam and Glycerin ....... 200

Imbedding in Paraffin .......... 202

Sectioning 204

Staining on the Slide 207

CULTURE METHODS

The Culture of Algje 211

The Culture of Fungi 212

The Culture of Liverworts and Mosses 215

The Culture of Ferns 216

The Culture of Seed Plants 216



CONTENTS

MATERIAL, APPARATUS, AND SUPPLIES

Lists of Preparations for the Microscope ....

Suggestions on Material for the Study of Plant Histology

Apparatus for the Laboratory

Chemicals for the Laboratory

Dealers in Material, Apparatus, and Supplies



vu



Page
. 217
. 220
. 222
. 224
. 225



BIBLIOGRAPHY 227

APPENDIX 2^^

GLOSSARY 2^^

INDEX 2^^



LIST OF EXPERIMENTS



I. Temperature and germination
II. Amount of water in seeds

III. Relation of air to germination

IV. Effect of germination on air .
V. Use of the pea cotyledons after germination

VI. Relation of food in seed to rate of growth
VII. Occurrence of starch in seeds
VIII. Oil in flaxseed . . • • •

IX. Proteids in seeds

X. Plant foods in Brazil nuts
XI. Cause of arch of hypocotyl .
XII. Discrimination between root and hypocotyl

XIII. Growing region of root ....

XIV. Percentage of water in the plant body .
XV. Water cultures

XVI. Root absorption with diminished temperature
XVII. Region of bending in the root
XVIII. Pressure of root tip ....

XIX. Cause of downward growth of root

XX. Osmosis

XXI. Osmosis of Begonia leaf ....
XXII. Course of water in stems

XXIII. Relation of loss of water to firmness of tissues

XXIV. Use of cork



Page

. 19

. 20

. 21

. 21

. 21

. 22

. 24

. 25

. 26

. 26

. 27

. 28

. 28

. 33

. 33

. 34

. 35

. 35

. 36

. 36

. 37

. 45

. 46

. 47



VIU

XXV.

XXVI.

XXVII.

XXVIII.

XXIX.

XXX.

XXXI.

XXXII.

XXXIII.

XXXIV.

XXXV.

XXXVI.

XXXVII.

XXXVIII.

XXXIX.

XL.

XLI.

XLII.



CONTENTS

Reserve sugar in onion bulb

Proteids in onion bulb

Cause of nocturnal position of leaves ....
Values of illumination for leaf positions
Adaptation of growing leaves to changed light relations
Heliotropic movements of English ivy



Pagb
. 48
. 48
. 53
. 53
. 54
. 55



Oxygen making by plants 57

Starch in Tropceolum leaves 57

Consumption of starch in Tropmolum leaves . . .58
Effect of sealing stomata on starch production . . .59
Effect of darkness on chlorophyll production . ^ . .69

Transpiration 60

Side of Ficus elastica leaf which transpires . . .61

Relative transpiration of Hydrangea Hortensia and Ficus

elastica 61

Passage of water from stem to leaf 63

Rise of water in leaves 63

Starch contents of leaves at various seasons . . .63
Production of pollen tubes 68



LABOEATOEY AND FIELD
MANUAL OF BOTANY

INTRODUCTION

It is intended that these laboratory outlines shall be found
adaptable to several methods of approach in framing a general
course in elementary botany.

First. By beginning with Part I the student may consider first
the more general features of the morphology of the seed plant
and the most important of its physiological activities. This
may then be followed by studies of a series of spore plants
(Part II), to outline the chief steps in plant evolution. Such work
as is possible in plant ecology (Part III) is thus deferred to the
end of the course.

Second. By commencing with Part II the student will be
introduced at once to the principles of cell structure, growth, and
reproduction, and can then trace the evolution of the plant king-
dom. By this arrangement selections from Part I will follow the
studies of Part II, and Part III will receive attention last.

Third. Part I may be followed at once by Part III, and the
studies of Part II be used only to illustrate such types and topics
concerned with spore plants as may seem desirable.

Fourth. It is by no means necessary that the matter of Part I
be taken up in the order given. Instead of beginning with the
plant as a whole or with the seed, a course may be readily shaped
so as to commence with the fruit or with the leaf.

The planning of a course depends upon so many factors, such as
season, material, equipment, maturity of students, and the time

1



2 INTRODUCTION

at the disposal of the class, that it must vary greatly with the
different conditions. The authors, recognizing these difficulties,
have tried to present a flexible outline in a thoroughly practical
manual containing sufficient material to permit of a wide range
of choice. In general they believe that the best results wdll
be obtained, when a full year can be devoted to the subject, by
taking the matter in the order given in the first or second of
the alternatives presented above. If only a half year is avail-
able, the best course in their judgment is that indicated in the
third alternative.

For the guidance of any who niaij care for such suggestions the
authors have designated hij double asterisks (**) those experiments
and studies which the// consider to he the most valuable.

A brief discussion of laboratory methods and equipment is
presented immediately before the laboratory outlines and experi-
ments of Parts I, II, and III. It is hoped that the instructor may
find some helpful suggestions in this, and certain parts are
written expressly to aid the student to an understanding of the
spirit ( of laboratory work, methods of drawing, note taking, and
the care of instruments.

The essential methods of botanical microtechnique and the
preparation of the material are taken up after the laboratory out-
lines. This account has been introduced to assist the instructor
and the advanced student in the collection and preservation of
material and in the more detailed studies of plant histology and
cytology, which demand the preparation of microtome sections
and critical staining methods. The discussion does not attempt
to give such details covering special studies as may be found in
several more exhaustive treatises to which the reader will be
referred. It endeavors rather to outline standard methods of
killing, fixing, preserving, cutting, and staining plant structures,
which cannot fail to give good results, with the reasons why
they have been selected. Some simple directions for the culture
of alg£e, fungi, moss protonema, fern prothallia, etc., follow the
account of microtechnique.



INTRODUCTION 3

A section entitled '' Material, Apparatus, and Supplies " gives
lists of preparations for the microscope, favorable material for
histological work, apparatus and supplies, with the addresses of
dealers who furnish these to the trade.

The bibliography has been chosen with the purpose of present-
ing a group of books many of which are within the possibilities
even of a well-equipped school library, rather than a lengthy list
of detailed literature which is usually only handled by the spe-
cialist. These works are numbered and the references to them
throughout the manual will be by the author's name and the
number.

An appendix with suggestions to instructors follows the bibliog-
raphy. This contains matter which it is not necessary for the
student to read in connection with his laboratory work, although
in many cases it may be of interest for him to do so. The ap-
pendix is really a collection of practical notes based on the
experience of the authors or gathered from conversations and
correspondence with many teachers. Indeed, it is a feature which
the authors have introduced in the hope that it may bring forth
other helpful and practical suggestions from those who use the
book, and correspondence upon this subject is cordially invited.

A glossary gives a selected list of botanical terms, including
the most important of those used in this manual and in the
authors' Principles of Botany.

Only a few necessary abbreviations have been used, to econo-
mize space. As stated above, books listed in the bibliography
are referred to by the author's name and number in the list.
Pi'inciples designates the Principles of Botany ; App., the ap-
pendix ; l.p., m.p., and h.p. refer to low power, medium power,
and high power of the compound microscope respectively ; lens
means either hand lens or dissecting microscope as the case may
be ; c.p. means chemically pure. The usual abbreviations for
the units of the metric system are frequently employed.



LABORATORY METHODS AND EQUIPMENT
The Laboratory and its Equipment

The essentials of a laboratory are, of course, good light, con-
venient tables, and sufficient apparatus. While north light is
preferable, since its quality is more constant, east, west, or south
light can be perfectly regulated by translucent shades wliich may
be pulled up to any desired distance, and so temper direct sun-
light when necessary. Moreover, it is desirable that some win-
dows have the sun for part of the day, since aquaria and glass'
cases for growing plants require some sunlight and may be placed
in such parts of the room. Excellent suggestions on the arrange-
ment of laboratory tables, lockers, glass growing case, sink, black-
board, etc., are given in Ganong, 7, Chapter V, and in Lloyd, 8,
Chapter IX, books which should be read by every teacher of botany.

The equipment of a laboratory will depend largely upon the
nature of the work, whether very elementary or covering a strong
full course of a year or more, and also upon the attitude of the
instructor, who may emphasize especially either physiology or a
more detailed morphology. Physiology requires its own special
apparatus, and detailed morphology demands the equipment
necessary for imbedding, microtome section cutting, and staining.
Much of the work with this apparatus can best be conducted at
tables in the center or back of the laboratory, which will not
interfere with the tables for the more general class exercises. In
the choice of equipment and its storage the instructor is again
referred to the admirable discussions of Ganong and Lloyd.
Lists of the chemicals, apparatus, and supplies necessary for the
work outlined in this manual are given in Sees. 215, 216.

The cost of compound microscopes is the item of greatest
expense in the equipment of a laboratory, and their selection

4



GKOWING PLANTS IN THE LABORATORY 5

tleraaiids careful thought. The laboratory should have enough
microscopes so that every student in a section may have his own
instrument. If this is not possible, it is better that the course
should be planned along such lines that the microscopic work
is largely in the nature of demonstrations by the instructor
on such microscopes as are available. Two or three students
working together at the same microscope create confusion and
secure poor results. There are a number of medium-priced instru-
ments on the market, with varying merits, from wliich the
instructor must choose for himself. A list of the more prominent
firms and agents is given in Sec. 218. It is false economy to
attempt to save expense on microscopes at the cost of workman-
ship and convenience in form. A set of microscopes may readily
be kept on the laboratory tables, protected from the dust when
not in use by paper cones, and used by successive sections,
although this system demands much more watchfulness on the
])art of the instructor than when each student has his own
instrument and is held responsible for its care.

Growing Plants in the Laboratory

Window sills and unused space should be utilized as far as
possible for keeping fresh and growing material alive in the
laboratory, not only for the interest that it arouses but also as
a practical matter of foresight which at times saves much diffi-
culty. Large jars covered with plate glass make excellent aquaria
and give little or no trouble. A surprising number of forms
will appear in them from time to time, and very interesting
cultures frequently become established. A glass growing case
(Wardian case) such as is described by Ganon(j, 7, p. 82, is a
most useful piece of equipment, and practically indispensable
for much physiological work when conservatories or greenhouses
are not available. A bay window shut off from the rest of
the room by tight glass screens is better still if the heat can
be regulated.



6 LABORATORY METHODS AND EQUIPMENT

Laboratory Material, Preparations, and
Collections

a laboratory should be kept well stocked with material and
slides sufficient for its work so that the instructor is never at a
loss for them. Some material and slides will probably have to be
purchased, and a list of dealers in botanical supplies is given in
Sec. 217. However, very many instructors will depend chiefly on
their own preparations and collections, and it is very desirable
that they do so. Material collected and prepared by oneself will
be generally better known and better taught than that from
dealers. The secret of keeping a laboratory well stocked is the
foresight which never loses the opportunity to preserve a fortu-
nate collection. The simpler methods of killing and preserving
material are given in Sec. 172. There are no great difficulties of
technique, and it is the experience of every botanist that mate-
rial will come to hand from time to time that is far better than
the average of that offered by the dealers. A laboratory should
always have large bottles of stock solutions of the simpler kill-
ing reagents (such as chrom-acetic acid) and preserving fluids
(such as alcohol) and a supply of wide-mouthed bottles and jars.
With this simple equipment at hand the instructor should be
constantly on the watch for opportunities to increase and improve
the laboratory stock. Thoughtfulness in this direction will save
much time and expense in the long run.

It is becoming desirable and even necessary to study many
points of detailed morphology and cell structure from slides.
These can be purchased singly or in sets from dealers (Sec. 217)
and the preparations are generally good ; however, the instructor
is urged to be self-reliant. The simpler methods of killing, im-
bedding, cutting, and staining are not difficult and are outlined
in the sections entitled Botanical Microtechnique. An advanced
student under direction can profitably be employed from time to
time in the service of slide making with excellent returns for the
expenditure involved. But more important is the added value



LABORATORY METHODS 7

of working with material that is thoroughly familiar. There is
danger in depending too much on slides, and they should not be
used where the student may readily make temporary prepara-
tions, for much of the value of laboratory work lies in the devel-
opment in the student of a certain manual skill. It is, however,
still more important that he become acquainted with and study
material first-hand. Botany made too easy by doing for the stu-
dent what he can do for himself is botany robbed of certain of
•its most obvious advantages as a laboratory study.

Some instructors are making considerable use of the lantern
and photographs, especially to illustrate ecological subjects, and
for this purpose they are of the greatest service. Large and
varied selections of lantern slides may be purchased (Sec. 219).
Charts have their evident value and there are some excellent,
although expensive, sets published (Sec. 219). It is not difficult
to make simple charts and diagrams even in colors {^Ganong, 7,
p. 115), and these may be adapted to the particular needs of the
course and cost almost nothing.

The herbarium and museum are most useful adjuncts to the
laboratory. Especially important is demonstration material of
groups which cannot be studied in many regions from living
plants, as, for example, the marine algse. Such material, either
in the form of herbarium sheets or on exhibition in museum
cases, forms a most useful part of the equipment of a botanical
department. The advantages of collections covering the local
flora are too obvious to need discussion. These matters are well
treated by Ganong, 7, Chapter VI.



Laboratory Methods

The laboratory work, with its accompanying notes, should
be kept absolutely separate from the text reading. Text-books
should not be allowed on the laboratory tables. Their function
is to present systematized accounts and conclusions after the
student has obtained a sufficient first-hand knowledge of the



8 I.AP.OJLVTOUV MHTllODS AND KQlIl'MENT

facts from the plants themselves, and to weld into one systematic
whole the somewhat isolated topics of laboratory study. Tt is
essential to good laboratory methods that the drawing and writing
of notes be done in the laboratory, which should be regarded as
a study room, like a library, open to the student as many hours
of the day as is possiWe, and every encouragement should be
t^iven to extended individual work.



The Labokatory Equipment of Each Student

Every student should have an individual equipment, kept
either in the drawers of the table or in lockers at the side of the
laboratory. The following essential instruments and supplies
had best be purchased by himself.

1. A razor, scalpel, forceps, and pair of needles.

2. Slides and cover glasses.

3. Tour solid watch glasses or salt dishes.

4. Two pipettes (medicine droppers), a camel's-hair brush,
and a scale in centimeters, millimeters, and inches.

5. A medium pencil (4H) or two pencils, hard (6H) and rather
soft (3H), eraser, mapping pens, liquid India ink, red ink, and
blue ink. Several colored pencils will be found very useful if the
student is to construct diagrams illustrating life histories and other
topics (App., 18). Higgins' red-label India ink runs more smoothly
and is generally more satisfactory than the waterproof ink.

6. Drawing paper and notebook. The drawings required may
be made on loose sheets kept in a folder, and the notes in a
book, but it has generally proved more convenient to use per-
forated sheets of both drawing paper and note paper, cut to the
same size, which can be loosely held together between stiff covers



Online LibraryJoseph Y. (Joseph Young) BergenLaboratory and field manual of botany → online text (page 1 of 24)