Elements of Structural and Systematic Botany. Douglas Houghton Campbell
topics of all the departments of botany. As a thorough understanding of the structure of any organism forms the basis of all further intelligent study of the same, it has seemed to the author proper to emphasize this feature in the present work, which is professedly an introduction, only, to the science.
This structural work has been supplemented by so much classification as will serve to make clear the relationships of different groups, and the principles upon which the classification is based, as well as enable the student to recognize the commoner types of the different groups as they are met with. The aim of this book is not, however, merely the identification of plants. We wish here to enter a strong protest against the only too prevalent idea that the chief aim of botany is the ability to run down a plant by means of an “Analytical Key,” the subject being exhausted as soon as the name of the plant is discovered. A knowledge of the plant itself is far more important than its name, however desirable it may be to know the latter.
In selecting the plants employed as examples of the different groups, such were chosen, as far as possible, as are everywhere common. Of course this was not always possible, as some important forms, e.g. the red and brown seaweeds, are necessarily not always readily procurable by all students, but it will be found that the great majority of the forms used, or closely related ones, are within the reach of nearly all students; and such directions are given for collecting and preserving them as will make it possible even for those in the larger cities to supply themselves with the necessary materials. Such directions, too, for the manipulation and examination of specimens are given as will make the book, it is hoped, a laboratory guide as well as a manual of classification. Indeed, it is primarily intended that the book should so serve as a help in the study of the actual specimens.
Although much can be done in the study, even of the lowest plants, without microscopic aid other than a hand lens, for a thorough understanding of the structure of any plant a good compound microscope is indispensable, and wherever it is possible the student should be provided with such an instrument, to use this book to the best advantage. As, however, many are not able to have the use of a microscope, the gross anatomy of all the forms described has been carefully treated for the especial benefit of such students. Such portions of the text, as well as the general discussions, are printed in ordinary type, while the minute anatomy, and all points requiring microscopic aid, are discussed in separate paragraphs printed in smaller type.
The drawings, with very few exceptions, which are duly credited, were drawn from nature by the author, and nearly all expressly for this work.
A list of the most useful books of reference is appended, all of which have been more or less consulted in the preparation of the following pages.
The classification adopted is, with slight changes, that given in Goebel’s “Outlines of Morphology and Classification”; while, perhaps, not in all respects entirely satisfactory, it seems to represent more nearly than any other our present knowledge of the subject. Certain groups, like the Diatoms and Characeæ, are puzzles to the botanist, and at present it is impossible to give them more than a provisional place in the system.
If this volume serves to give the student some comprehension of the real aims of botanical science, and its claims to be something more than the “Analysis” of flowers, it will have fulfilled its mission.
DOUGLAS H. CAMPBELL.
Bloomington, Indiana,
October, 1889.
BOTANY.
CHAPTER I.
INTRODUCTION.
All matter is composed of certain constituents (about seventy are at present known), which, so far as the chemist is concerned, are indivisible, and are known as elements.
Of the innumerable combinations of these elements, two general classes may be recognized, organic and inorganic bodies. While it is impossible, owing to the dependence of all organized matter upon inorganic matter, to give an absolute definition, we at once recognize the peculiarities of organic or living bodies as distinguished from inorganic or non-living ones. All living bodies feed, grow, and reproduce, these acts being the result of the action of forces resident within the organism. Inorganic bodies, on the other hand, remain, as a rule, unchanged so long as they are not acted upon by external forces.
All living organisms are dependent for existence upon inorganic matter, and sooner or later return these elements to the sources whence they came. Thus, a plant extracts from the earth and air certain inorganic compounds which are converted by the activity of the plant into a part of its own substance, becoming thus incorporated into a living organism. After the plant dies, however, it undergoes decomposition, and the elements are returned again to the earth and atmosphere from which they were taken.
Investigation has shown that living bodies contain comparatively few elements, but these are combined into extraordinarily complex compounds. The following elements appear to be essential to all living bodies: carbon, hydrogen, oxygen, nitrogen, sulphur, potassium. Besides these there are several others usually present, but not apparently essential to all organisms. These include phosphorus, iron, calcium, sodium, magnesium, chlorine, silicon.
As we examine more closely the structure and functions of organic bodies, an extraordinary uniformity is apparent in all of them. This is disguised in the more specialized forms, but in the simpler ones is very apparent. Owing to this any attempt to separate absolutely the animal and vegetable kingdoms proves futile.
The science that treats of living things, irrespective of the distinction between plant and animal, is called “Biology,” but for many purposes it is desirable to recognize the distinctions, making two departments of Biology—Botany, treating of plants; and Zoölogy, of animals. It is with the first of these only that we shall concern ourselves here.
When one takes up a plant his attention is naturally first drawn to its general appearance and structure, whether it is a complicated one like one of the flowering plants, or some humbler member of the vegetable kingdom—a moss, seaweed, toadstool—or even some still simpler plant like a mould, or the apparently structureless green scum that floats on a stagnant pond. In any case the impulse is to investigate the form and structure as far as the means at one’s disposal will permit. Such a study of structure constitutes “Morphology,” which includes two departments—gross anatomy, or a general study of the parts; and minute anatomy, or “Histology,” in which a microscopic examination is made of the structure of the different parts. A special department of Morphology called “Embryology” is often recognized. This embraces a study of the development of the organism from its earliest stage, and also the development of its different members.
From a study of the structure of organisms we get a clue to their relationships, and upon the basis of such relationships are enabled to classify them or unite them into groups so as to indicate the degree to which they are related. This constitutes the division of Botany usually known as Classification or “Systematic Botany.”
Finally, we may study the functions or workings of an organism: how it feeds, breathes, moves, reproduces. This is “Physiology,” and like classification must be preceded by a knowledge of the structures concerned.
For the study of the gross anatomy of plants the following articles will be found of great assistance: 1. a sharp knife, and for more delicate tissues, a razor; 2. a pair of small, fine-pointed scissors; 3. a pair of mounted needles (these can be made by forcing ordinary sewing needles into handles of pine or other soft wood); 4. a hand lens; 5. drawing-paper and pencil, and a note book.
For the study of the lower plants, as well as the histology of the higher ones, a compound microscope is indispensable. Instruments with lenses magnifying from about 20 to 500 diameters can be had at a cost varying from about $20