Introduction to elementary practical biology; a laboratory guide for high-school and college students

Introduction

TO

ELEMENTARY PRACTICAL

BIOLOGY

H Xaborators 6utt>e

tor

UMab^Scfcool anD College Students

BY /

PROFESSOR OF BIOLOGY IN THE UNIVERSITY OF ROCHESTER

HARPER & BROTHERS PUBLISHERS

Copyright, 1894, by Harper & Brothers.

All rights reserved.

nature, not books.''' 1 — Agassiz

" Real knowledge in science means a personal acquaintance with the facts, be they few or many.' 1 '' — Huxley

" TJie ideal of scientific teaching is, no doubt, a system by which the scholar sees every fact for himself and the teacher supplies only the explanations." — Huxley

Preface

Students, particularly those of the natural sciences, are no longer satisfied to receive didactic instruction, but want the training which will fit them for investigation. In Biology it is the custom to furnish such training by having the student verify the facts acquired by professional investigators. The methods of teaching now in vogue for elementary classes are methods of instruction rather than of education. The student gets the most of his knowledge from books or from lectures, and very little from specimens. When thrown upon his own resources, as when called upon to examine some natural object and to describe it in his own language, he is entirely powerless. If he can find in some book a description of the object, he may, perhaps, be able to verify it, and, using that in the book as a pattern, to write a description of his own.

A method of teaching which consists solely of the verification of the printed statements often leads students into temptation, for there are always a few who have too little mental strength and moral courage to resist using as their own the facts given in books, particularly when it comes to dissecting a difficult organ or to tracing a minute duct. Not a few students who

VI PEEFACE

have been taught by the "verification method" have confessed committing to memory the detailed descriptions of their specimens in preference to doing the work necessitated by a practical examination. It is needless to say that with such students laboratory work fails completely to accomplish its fourfold object — viz., to teach the student, first, to observe correctly; second, to distinguish essential from non-essential facts ; third, to draw proper conclusions from the facts observed ; and fourth, to express in writing and by means of drawings the results obtained.

For the purpose of developing in the student the power of independent observation, to teach him that the source of all knowledge is not "the book" rather than the specimen, that there is a great deal to be seen besides that which "the book" describes, and that he is not to consider that, though his observations may not agree with those of "the book," the latter must, necessarily, be right — these are the reasons why this guide has been written.

The guide consists essentially of questions on the gross and minute structure and on the physiology of a series of common animals and plants which are typical of their kind — questions which can be answered only by actual examination of the specimen or by performance of the experiment. Directions are given for the collection of specimens, for their preservation, and for preparing them for examination, also for performing simple physiological experiments. Particular species are not required, as the questions usually apply equally well to several related forms.

PKEFACE Vll

The material of which the guide is composed has been gradually accumulated during an experience of nearly seven years of teaching high-school and college classes, consisting of students of both sexes and of ages varying from fourteen to fifty years. With the exception of a few additions made while preparing the manual for printing, all of the work herein detailed has been performed by college students, and a very large part by students in the second year of their high-school course.

Although it is thought that the topics are so arranged and the questions so worded that any one of average intelligence can study any or all of the organisms given, still it is not intended that the guide shall supersede the instructor, but, rather, aid him. The student will always require the advice and suggestions of his teacher, who will need to point out many of the structures which here are only named, and which it would be impossible to describe so that the student could find them for himself, without defeating the very object which the guide seeks to attain.

As this manual has to do entirely with the work of the laboratory, it is suggested to those teachers who wish to use a text-book also, that nothing better can be found than Parker's admirable work, " Lessons in Elementary Biology," 2d ed., New York, 1893.

Following the classification given in the " Text-Book of Zoology" of Glaus and Sedgwick, and the "Outlines of Classification and of Special Morphology of Plants " of Goebel, an attempt has been made to arrange in logical sequence the organisms to be studied, proceeding from the simple to the more complicated. It is desira-

Vlll PREFACE

ble that they should be studied in this order. Experience has shown that this method can be pursued with little or no difficulty and to the greatest advantage. It is very frequently the case, as here, that the simplest form is not necessarily the best known. Every one is more familiar — by sight, at least — with the frog than with the amoeba. The structure of the former resembles that of the human body far more than does that of the latter. But how many students have even the most general knowledge of human anatomy ? They know, to be sure, that the body contains a heart, lungs, stomach, etc., but in the great majority of cases would fail to locate or, if shown them, even to recognize these organs. Again, how many students, if called upon to do so, could tell more about the frog than that it usually lives in the water, is greenish in color, has four legs, a mouth, etc., and can jump and swim ? Whether or not the frog has a tail is usually a question for discussion. As a matter of fact, beginning students have no more real knowledge of the higher than of the lower forms.

That the student is unaccustomed to the use of the microscope is often urged as a reason against beginning with minute organisms. Does his study of the gross anatomy of a rabbit or of a frog teach him anything about the manipulation of this instrument ? Sooner or later he will have to learn to use it, and it matters little when he does so ; the instrument will be unfamiliar to him until he actually handles it and learns its use by degrees. He should approach it by way of the magnifying glass, and use the low before attempting the high powers. In two hours the average student can learn

PREFACE IX

sufficient of manipulation to warrant trusting him with a microscope. His power of observation will be developed only by training. It is advisable to begin with the lower forms, not only because of their simplicity of structure, but also because of the value of this method in tracing the development both morphologically and physiologically of the tissues and organs of the higher organisms and the evolution of forms. Though this plan seems preferable, it is not absolutely necessary that it should be followed. The student may begin with the highest form and work downward ; or he may commence with an intermediate form and work either way ; again, he may begin with an intermediate form, then go to the lowest and work upward. On account of lack of instruments, it may be necessary to omit all of the minute organisms and all of the microscopic work on the higher forms. It is thought that the guide can readily be adapted to any of these methods. The end to be attained is not to examine as many specimens as possible, but to examine them as thoroughly as possible.

It has been found that the question stimulates the student to a degree of mental endeavor far beyond that attained by the attempt to verify a printed statement. A few of the questions are suggestive rather than capable of a definite answer, but these will be found to have their use. The notes made in the laboratory should form the basis of the recitation, and many of the topics should be further elaborated and discussed by the teacher.

]\Iuch of the pleasure and instruction to be derived

X PREFACE

from the examination of living organisms is lost because few people know how and what to observe. To most individuals the study of Natural History means nothing more than the memorizing of Latin names, of long descriptions consisting of unfamiliar terms, of " collecting " various kinds of disagreeable creatures, and preserving them dried or in alcohol, etc., etc.

Should this guide, even in the slightest degree, prove instrumental in doing away with such a belief and in cultivating a taste for the study of nature, then will it have accomplished its purpose.

In one of the appendices is given, under its appropriate heading, a list of literature which the student may profitably consult after having finished the study of each organism. In the construction of the guide free use has been made of the works named. In another appendix is given a brief list of the reagents and some of the appliances needed in carrying out the work given in the body of the manual. For more detailed directions and descriptions the student is referred to the works on microscopical technique and laboratory methods.

Acknowledgment is due to Mr. Arthur Willey, of Columbia College, who kindly looked over the proofsheets and made a number of valuable suggestions.

C. W. D.

Contents

INTRODUCTION

Suggestions — Apparatus required by the Student — Dissection — Taking Notes — Drawing — Using the Microscope pages xvii.-xxiii

Part I I THE ANIMAL CELL, ITS MOEPHOLOGY AND PHYSIOLOGY

A. — The Unicellular Animals

Example 1. — The Protozoa: General questions. Example 2. — The Proteus Animalcule : Morphology — size, shape, structure ; Physiology — movements, nutrition, sensation, reproduction ; General questions. Example 3. — The Slipper Animalcule: Morphology — shape, size, structure; Physiology — movements, nutrition, nervous properties, reproduction; General questions. Example 4. — The Bell Animalcule : Morphology — shape, size, structure ; Physiology — movements, nutrition, nervous properties, reproduction ; General questions 3-20

B. — Cells isolated from the Bodies op Multicellular Animals

Example 5. — Salivary Cells: Morphology — general structure; Physiology — motion, nutrition. Example 6. — Blood Cells: Morphology — red cells, colorless cells; Physiology — movements, ingestion, effects of temperature. Example 7. — Ciliated Cells : Morphology — general structure ; Physiology — movements, ingestion; General questions 21-27

Xll CONTENTS

II THE PLANT CELL, ITS MORPHOLOGY AND PHYSIOLOGY

A. — The Unicellular Plants

Example 1. — Yeast: Morphology — arrangement, shape, size, color, structure, iodine test for detecting the presence of starch ; Physiology — effect of food-supply upon growth, effect of temperature upon growth, effect of light upon growth, nature of the gas given off by the growing yeast, formation of alcohol, chemical reaction of fluid yeast, temperature of yeast during growth, effect of filtered yeast upon a fermentable fluid, reproduction ; General questions. Example 2. — Green Slime: Morphology — Naked-eye characters — occurrence, color, structure ; Microscopic characters, Vegetative condition — arrangement, shape, size, color, structure, tests for cellulose; Reproductive condition ; General questions. . .28-46

B. — Cells isolated prom the Bodies of Multicellular Plants

Example 3. — Spores of Fungi : Morphology — general structure ; Physiology — germination ; General questions. Example 4. — Pollen Grains : Morphology — general structure ; Physiology — germination. Example 5. — Water Silk: Morphology — Vegetative condition — Naked-eye characters, Microscopical characters — the shape of the filament, the structure of the individual filament, the structure of the individual cell ; Reproductive condition — general appearance, structure of the fruiting filament, position of the fruiting filament, the conjugating tubes, the zygospores; Physiology — formation of starch, effect of light, effect of carbon dioxide, growth, cell-formation ; General questions 46-61

Part II THE BIOLOGY OF THE ANIMAL SPONGES

Example 1. — Skeleton of Toilet Sponge: Morphology — shape, size, color, elasticity and porosity, structure. Example 2. — Fresh-water Sponge: Morphology — shape, size, color, structure ; Physiology — movements, ingestion ; General questions. Examples. — Grantia: Morphology — )e, size, color, structure 65-79

CONTENTS Xlll

FRESH-WATER POLYP

Morphology — size, shape, color, structure; Physiology — movements, nutrition, nervous properties ; Microscopic structure 80-89

CAMPANULARIAN HYDROID

Morphology — general form and structure, perisarc, ccenosarc, zooids ; Physiology — movements, feeding, sensation ; General questions 90-96

STAEFISH

Morphology — External anatomy — shape, size, color, structure; the skeleton; Internal anatomy — the digestive system, the reproductive system, the water- vascular system, the circulatory system, the respiratory system, the nervous system ; Physiology — movements, nutrition, nervous properties, reproduction, regeneration of lost portions of the body, sexual reproduction, the structure of the sexual cells, preparation of the ovum for fertilization, fertilization, the consequences of fertilization 97-121

EAETHWOEM

Morphology — External characters — general shape, color, general structure, apertures ; Internal anatomy — the digestive system, the circulatory system, the nervous system, the excretory system, the reproductive system ; Physiology — movements, feeding, circulation; General questions. . .122-137

Morphology — External characters — the entire animal, the body proper, the abdomen, the cephalothorax, the telson, the appendages, the gill-chamber, the exoskeleton, the organs of special sense ; Internal anatomy — the epidermis, the muscular system, the circulatory system, the digestive system, the excretory system, the reproductive system, the nervous system ; Physiology — movements, feeding, breathing, nervous properties; General questions 188-171

Morphology — the body as a whole, the head, the mouth-parts, the thorax, the abdomen ; Internal anatomy — the muscles, the viscera, the nervous system ; Physiology ; General questions 172-188

XIV CONTENTS

MOLLUSC SHELLS

Example 1. — Fresh-water Mussel: General structure. Example 2. — Pond Snail : General structure 189-193

THE SOFT PARTS OF THE FRESH-WATER MUSSEL

External anatomy ; Internal anatomy — the digestive system, the circulatory system, the nervous system, the excretory system ; The examination of transverse sections ; Habits 194-202

FROG

Morphology — External anatomy— shape, size, color, general structure; Internal anatomy — the skeleton, the muscular system, the digestive system, the respiratory system, the urino-genital system, the circulatory system, the external anatomy of the heart, the veins, the arteries, the internal anatomy of the heart, the lymph hearts, the nervous system, general structure, the central nervous system, the peripheral nervous system ; the eye and the ear; Microscopic anatomy; Physiology — locomotion, nutrition, development 203-263

Part III THE BIOLOGY OF THE PLANT GREEN FELT

Morphology — Vegetative condition, Naked-eye characters, Microscopic characters, Reproductive condition ; General questions 26*7-272

STONEWORT

Morphology — Naked-eye characters, Microscopic structure; Physiology — growth, movements of protoplasm ; General questions 273-284

ROCKWEED

Morphology — Naked-eye characters, Microscopic examination ; Physiology — the fertilization of the oosphere; General questions 285-296

CONTENTS XV

MOULD

Morphology — Naked-eye characters, Microscopic characters; Physiology — the germination of the conidia ; General questions 297-300

MUSHROOM

Morphology — Naked-eye characters, Microscopic structure ; General questions 301-307

Morphology — Naked-eye characters, Microscopic structure; Physiology — the fertilization of the oosphere 308-319

FERN

Morphology — The Spore-bearing, or Asexual Plant : Naked-eye characters, Microscopic structure. The Prothallium or Sexual Generation. Physiology, the germination of the spore and the development of the prothallium 320-335

THE FLOWERING PLANT

Seeds: Morphology — bean, other seeds, some of the chemical contents of dry seeds, microscopic examination of starch and aleurone ; Physiology — imbibition and turgescence, germination, geotropism, respiration, temperature of germinating seeds, some of the chemical contents of germinating seeds, action of the diastase of malt upon starch, osmosis. Stems : Morphology — Naked-eye characters, Microscopic structure ; Physiology — movements, direct observation of the ascent of water in the stem. Roots. Buds : Morphology — Naked-eye characters, Microscopic characters. Leaves: Morphology- — Gross anatomy, Microscopic characters; Physiology — transpiration, assimilation, movements. Flowers: Morphology — Naked-eye characters, Microscopic structure; Physiology — fertilization 336-377

Appendix

INTRODUCTION

Every student should have assigned him a definite place to work, for whose good order he should be held responsible; also a drawer in which to keep his instruments, note-books, etc. The drawer ought to be provided with a lock to which no one but the student and the instructor has the key. The most convenient place for the drawer is in the table at which the student sits, as here it is more easily accessible than elsewhere. If necessary, a case of drawers may be placed at some convenient place in the room.

The laboratory exercises should be at least two consecutive hours in length, as so much time is consumed in making the preparations for work and in " cleaning up " afterwards that but little can be accomplished in one hour, while an exercise which lasts three hours is very likely to fatigue the beginning student unduly.

A certain fee ought to be charged for the use of microscopes and other apparatus, and for specimens, etc. Some wear and tear of instruments is to be expected, but any damage beyond this should be made good by the student.

Economy of material must be practised, but not to such an extent as to interfere with obtaining a clear idea of the structure of each organism. Each student should provide his own specimens of the commoner forms, e. g., earthworm, locust, and various plants. Before putting specimens into hardening reagents, be sure to see that the body and its appendages are properly arranged, otherwise they may stiifen in positions awkward for handling. Preserved specimens B

XV111 INTRODUCTION

of the marine forms may be obtained from the Department of Laboratory Supply of the Marine Biological Laboratory at Wood's Holl, Mass., or from Ward's Natural History Establishment, Rochester, N. Y.

Whenever possible, the living organism ought to be closely observed before any work is done on dead specimens. It is an excellent plan for the student to have a live specimen before him while studying the anatomy of dead material.

Apparatus required by the Student

Each student should provide himself with the following :

1. A medium-size and a small scalpel.

2. A pair of medium -size and a pair of small (oculist's) forceps, both with straight points and rough tips.

3. A pair of fine curved scissors, which should meet accurately at the tips.

4. A pair of dissecting needles, made by fastening the eye-end of stout sewing-needles into wooden penholders.

5. A razor.

6. Twenty-five slides and a half-ounce of cover-glasses.

7. Two note-books, one for making condensed notes while doing the laboratory work, the other in which to write in ink a full and carefully worded account of the observations made.

8. A number of cards of bristol-board cut to the size of a large postal-card. Upon these drawings are to be made. If desired, a blank-book of thick calendered paper may be used.

9. A hard pencil, either HHHHH or HHHHHH Faber is recommended.

10. A piece of india-rubber.

11. An apron, preferably of rubber.

12. A towel.

Dissection

The object of dissection is to separate the various parts in such a manner as to display their shape and mutual rela-

INTRODUCTION XIX

tions, and it consists almost entirely in the removal of the connective tissues which bind the different organs together. The student must plainly understand that hacking specimens to pieces is not dissection.

While dissecting, the following rules should be borne in mind ;

1. Fix the specimen in whatever position may be most convenient for work. If it be a large object, as, for example, a lobster or frog, lay it dorsal or ventral side uppermost as may be desired, and with the head turned away from one. If the specimen be so easily moved as to interfere with the work, stick pins obliquely through the softer tissues into the dissecting- tray or the wax in the bottom of the dissecting-pan.

2. The tissues of fresh specimens must be moistened from time to time with water or with normal salt-solution to prevent the drying and distortion of parts. Alcoholic material should be examined in dishes containing fifty per cent, alcohol. If such specimens be large, e. g., lobster, and it be desirable to examine them on the dissecting-tray, place them for two or three hours previous to the time when wanted in a mixture of equal parts of water, alcohol, and glycerine. They will then keep moist even in the open air.

3. Before making a cut in any direction, study the specimen carefully, and note where the cut must be made in order to expose the part wanted with the least injury to surrounding parts. Specimens unnecessarily mutilated should be replaced at the expense of the student.

4. In dissecting and cleaning muscles, nerves, and blood-vessels, stretch them slightly and work in the direction of their length, never crosswise.

5. Avoid unnecessary handling of the parts, and do not pinch them -with the forceps.

6. Do not allow scraps to accumulate on the specimen. Sponge away blood-clots. With a pipette wash away the debris which accumulates on specimens dissected under water, or change the water frequently.

XX INTEODUCTION

7. Good work cannot be done with dull instruments, therefore keep them clean and sharp.

8. When work is finished for the day, all instruments which have been used should be washed, or wiped with a damp cloth, to remove all adhering scraps of flesh, thoroughly dried with a soft cloth, then carefully oiled or rubbed with vaseline. The joints of the scissors should receive close attention.

It is a good plan to require each student to prepare a careful dissection of some animal or system of organs. These preparations may be used to form a laboratory museum.

Taking Notes

A complete and carefully prepared description must be made of every specimen examined. This description will consist mainly of answers to the questions given in the manual. To these are to be added whatever independent observations the student may make. If the answers be given in the same order as the questions are asked, it will be found that the former constitute a brief essay upon the organism examined.

Two note-books should be used, one in which to write hastily in the laboratory the results of the observations made ; the other to contain the carefully prepared descriptions which, written plainly in ink and with due regard to rhetorical form and expression, are intended for examination by the instructor and for permanent preservation. Make the laboratory notes full and complete, record the observation as soon as it is made, leave nothing to the memory; otherwise the second set of notes will suffer. In answering such questions as are mainly theoretical, give all the reasons you can pro and con.

Drawing

Draw every specimen examined and every dissection made. Endeavor to get correct outlines and relative posi-

INTRODUCTION XXI

tion of parts. Shading is seldom desirable. Draw everything to scale, and mark on the drawing the scale adopted. Always sketch in the outline faintly at first, then fill in the details. When the specimen is bilaterally symmetrical, draw a faint line to represent the median line, sketch the outline of the left, then of the right side, and fill in the details. Make every drawing large enough to show all of the parts plainly. Name every part or organ in every drawing. It adds much to the appearance and value of the drawings if they be colored with water-colors, using the dull tints for the larger and the bright colors for the small organs. In a set of drawings of the same specimen always use one color for the same system or organ. Indicate arteries in red, veins in blue, and other parts in their natural colors. Drawings must not be made too small.

Using the Microscope

1. Take the instrument from the case together with the eye-piece and objective to be used, then close the case and set it aside out of the way.

2. Examine every part of the instrument to be sure that it is clean. Wipe off the dust by brushing lightly with a soft clean cloth.

3. If there be anything but dust on the objective, wipe the latter with a soft, moist cloth, then dry immediately with a soft cloth. If this fail to remove the dirt, take the objective to the instructor. Do not use chamois skin or soiled cloths of any kind. A worn linen or silk handkerchief, kept perfectly clean and free from dust, is as good as anything that can be found to clean the microscope.

4. Put in the eye-piece ; screw on the objective.

5. Incline the tube at a convenient angle.

6. Turn the tube down to about one fourth of an inch from the stage. Be exceedingly careful to avoid contact of the front lens with the stage or with anything upon it.

XX11 INTRODUCTION

7. Arrange the mirror so as to throw the light which comes in at the windoio up through the opening in the middle of the stage. Do not use the direct sunlight.

8. Place the glass slide on the stage and under the clips, with the object over the centre of the opening. If the object be mounted in a fluid, see that none of the latter oozes out around the edge of the cover-glass, otherwise the objective may be soiled. Never use the high power to examine an object which is not protected by a cover-glass.

9. Turn the tube down nearly to the object.

10. While looking through the microscope, bring the object into focus by slowly turning the tube upward. Never do so by turning the tube downward.

11. Examine every object with the low power first; keep both eyes open when examining an object. This can be done after a little practice, and avoids unduly fatiguing the muscles which close the unused eye. Get into the habit of using either eye. With the low power use a large and with a high power a small diaphragm. Use the concave mirror for strong illumination. If foreign particles appear in the field, locate them by the following method : While looking into the instrument rotate the eye-piece in the tube ; if the particles also rotate, they are on or in the eye-piece and should be removed; if the particles do not rotate, move the slide; if the particles move, they are on the slide and must be wiped off. If the object looks hazy, the particles must be on the objective, which may be gently wiped; if this does not remove the difficulty, take the instrument to the instructor. While observing, vary the focus constantly with the fine adjustment. This method will give a far clearer idea of the object than to fix the focus once for all and to sit staring into the tube.

12. On quitting work, turn the tube up to about an inch above the stage, remove the slide, unscrew the objective and put it into its case, remove the eye-piece and return it to the box, straighten the instrument if it has been in-

INTRODUCTION XX111

clined, and place it in the case, being careful to lock the latter.

13. JVever touch the lenses or the mirror or the surface of the slide or cover-glass with the fingers. Wipe off dust with a soft cloth. Hold slides and cover-glasses by the edges.

Part I THE BIOLOGY OF THE CELL I

THE ANIMAL CELL, ITS MORPHOLOGY AND PHYSIOLOGY

A. — The Unicellular Animals Example 1. — The Protozoa

Material. — Specimens may be obtained in any of the following ways : by skimming the surface of the mud in the bottom of a pond or a slow -running ditch or brook ; by scraping the under surface of the leaves of water plants, as pond-lilies, duck-weed, etc. ; by squeezing the water out of clumps of fresh- water or marine algae, or out of damp sphagnum moss ; by tying a small bag of bolting -cloth or of fine muslin over the mouth of a Avater-tap, allowing the water to run slowly through the bag for fifteen minutes to an hour, then turning the bag wrong side out and rinsing the collected sediment into a dish containing a small amount of water ; by searching, under the microscope, the moist green film found growing on the surface of flower-pots, trunks of trees, and on the bricks or stones in the foundations of buildings ; by examining the fluid found in the mantle-cavity of oysters and clams ; by rinsing in artificial sea -water the gills of unboiled lobsters; by scraping the tongue and the roof of the mouth of frogs or ducks, or the gills of fishes a day or two after they are caught ; by rinsing the contents of the intestines of frogs, lobsters, crawfish, etc. Many marine forms may be caught by skimming the surface of the water with a net of bolting-cloth, especially on warm, quiet evenings. The most practicable method of supplying specimens for large classes is to resort to cultivations. Fresh -water forms may be raised in large numbers by cutting into a dish bits of hay, grass, marsh-grass, potato, fish- skin, moss, or, in fact, almost any organic substance, pouring over the pieces just enough lukewarm water to cover them, and setting the dish, covered to prevent evaporation, in a warm, not too light place for one to seven days. Another very satisfactory method is to allow fresh- water weeds and algae to decay in a small amount of water. Many marine forms may be cultivated by soaking in artificial sea-water for a few days bits of oysters, clams, and the gills of unboiled lobsters. As particular forms usually have definite habitats, it is best not to obtain all of the specimens from a single locality, but to gather them from as various sources as possible. In the cultivations some forms will be found at the edge of the dish at the surface, others on the bottom, others attached to the sides, some swimming freely, and still others fastened to the pieces of organic material.