NATURAL HISTORY TO THE TIME OF LINNAeUS
Modern systematic botany and zoology are usually held to have
their beginnings with Linnaeus. But there were certain precursors
of the famous Swedish naturalist, some of them antedating him by
more than a century, whose work must not be altogether
ignored--such men as Konrad Gesner (1516-1565), Andreas
Caesalpinus (1579-1603), Francisco Redi (1618-1676), Giovanni
Alfonso Borelli (1608-1679), John Ray (1628-1705), Robert Hooke
(1635-1703), John Swammerdam (1637-1680), Marcello Malpighi
(1628-1694), Nehemiah Grew (1628-1711), Joseph Tournefort
(1656-1708), Rudolf Jacob Camerarius (1665-1721), and Stephen
Hales (1677-1761). The last named of these was, to be sure, a
contemporary of Linnaeus himself, but Gesner and Caesalpinus
belong, it will be observed, to so remote an epoch as that of
Copernicus.
Reference has been made in an earlier chapter to the microscopic
investigations of Marcello Malpighi, who, as there related, was
the first observer who actually saw blood corpuscles pass through
the capillaries. Another feat of this earliest of great
microscopists was to dissect muscular tissue, and thus become the
father of microscopic anatomy. But Malpighi did not confine his
observations to animal tissues. He dissected plants as well, and
he is almost as fully entitled to be called the father of
vegetable anatomy, though here his honors are shared by the
Englishman Grew. In 1681, while Malpighi's work, Anatomia
plantarum, was on its way to the Royal Society for publication,
Grew's Anatomy of Vegetables was in the hands of the publishers,
making its appearance a few months earlier than the work of the
great Italian. Grew's book was epoch-marking in pointing out the
sex-differences in plants.
Robert Hooke developed the microscope, and took the first steps
towards studying vegetable anatomy, publishing in 1667, among
other results, the discovery of the cellular structure of cork.
Hooke applied the name "cell" for the first time in this
connection. These discoveries of Hooke, Malpighi, and Grew, and
the discovery of the circulation of the blood by William Harvey
shortly before, had called attention to the similarity of animal
and vegetable structures. Hales made a series of investigations
upon animals to determine the force of the blood pressure; and
similarly he made numerous statical experiments to determine the
pressure of the flow of sap in vegetables. His Vegetable Statics,
published in 1727, was the first important work on the subject of
vegetable physiology, and for this reason Hales has been called
the father of this branch of science.
In botany, as well as in zoology, the classifications of Linnaeus
of course supplanted all preceding classifications, for the
obvious reason that they were much more satisfactory; but his
work was a culmination of many similar and more or less
satisfactory attempts of his predecessors. About the year 1670
Dr. Robert Morison (1620-1683), of Aberdeen, published a
classification of plants, his system taking into account the
woody or herbaceous structure, as well as the flowers and fruit.
This classification was supplanted twelve years later by the
classification of Ray, who arranged all known vegetables into
thirty-three classes, the basis of this classification being the
fruit. A few years later Rivinus, a professor of botany in the
University of Leipzig, made still another classification,
determining the distinguishing character chiefly from the flower,
and Camerarius and Tournefort also made elaborate
classifications. On the Continent Tournefort's classification was
the most popular until the time of Linnaeus, his systematic
arrangement including about eight thousand species of plants,
arranged chiefly according to the form of the corolla.
Most of these early workers gave attention to both vegetable and
animal kingdoms. They were called naturalists, and the field of
their investigations was spoken of as "natural history." The
specialization of knowledge had not reached that later stage in
which botanist, zoologist, and physiologist felt their labors to
be sharply divided. Such a division was becoming more and more
necessary as the field of knowledge extended; but it did not
become imperative until long after the time of Linnaeus. That
naturalist himself, as we shall see, was equally distinguished as
botanist and as zoologist. His great task of organizing knowledge
was applied to the entire range of living things.
Carolus Linnaeus was born in the town of Rashult, in Sweden, on
May 13, 1707. As a child he showed great aptitude in learning
botanical names, and remembering facts about various plants as
told him by his father. His eagerness for knowledge did not
extend to the ordinary primary studies, however, and, aside from
the single exception of the study of physiology, he proved
himself an indifferent pupil. His backwardness was a sore trial
to his father, who was desirous that his son should enter the
ministry; but as the young Linnaeus showed no liking for that
calling, and as he had acquitted himself well in his study of
physiology, his father at last decided to allow him to take up
the study of medicine. Here at last was a field more to the
liking of the boy, who soon vied with the best of his
fellow-students for first honors. Meanwhile he kept steadily at
work in his study of natural history, acquiring considerable
knowledge of ornithology, entomology, and botany, and adding
continually to his collection of botanical specimens. In 1729 his
botanical knowledge was brought to the attention of Olaf Rudbeck,
professor of botany in the University of Upsala, by a short paper
on the sexes of plants which Linnaeus had prepared. Rudbeck was
so impressed by some of the ideas expressed in this paper that he
appointed the author as his assistant the following year.
This was the beginning of Linnaes's career as a botanist. The
academic gardens were thus thrown open to him, and he found time
at his disposal for pursuing his studies between lecture hours
and in the evenings. It was at this time that he began the
preparation of his work the Systema naturae, the first of his
great works, containing a comprehensive sketch of the whole field
of natural history. When this work was published, the clearness
of the views expressed and the systematic arrangement of the
various classifications excited great astonishment and
admiration, and placed Linaeus at once in the foremost rank of
naturalists. This work was followed shortly by other
publications, mostly on botanical subjects, in which, among other
things, he worked out in detail his famous "system."
This system is founded on the sexes of plants, and is usually
referred to as an "artificial method" of classification because
it takes into account only a few marked characters of plants,
without uniting them by more general natural affinities. At the
present time it is considered only as a stepping-stone to the
"natural" system; but at the time of its promulgation it was
epoch-marking in its directness and simplicity, and therefore
superiority, over any existing systems.
One of the great reforms effected by Linnaeus was in the matter
of scientific terminology. Technical terms are absolutely
necessary to scientific progress, and particularly so in botany,
where obscurity, ambiguity, or prolixity in descriptions are
fatally misleading. Linnaeus's work contains something like a
thousand terms, whose meanings and uses are carefully explained.
Such an array seems at first glance arbitrary and unnecessary,
but the fact that it has remained in use for something like two
centuries is indisputable evidence of its practicality. The
descriptive language of botany, as employed by Linnaeus, still
stands as a model for all other subjects.
Closely allied to botanical terminology is the subject of
botanical nomenclature. The old method of using a number of Latin
words to describe each different plant is obviously too
cumbersome, and several attempts had been made prior to the time
of Linnaeus to substitute simpler methods. Linnaeus himself made
several unsatisfactory attempts before he finally hit upon his
system of "trivial names," which was developed in his Species
plantarum, and which, with some, minor alterations, remains in
use to this day. The essence of the system is the introduction of
binomial nomenclature--that is to say, the use of two names and
no more to designate any single species of animal or plant. The
principle is quite the same as that according to which in modern
society a man has two names, let us say, John Doe, the one
designating his family, the other being individual. Similarly
each species of animal or plant, according to the Linnaeean
system, received a specific or "trivial" name; while various
species, associated according to their seeming natural affinities
into groups called genera, were given the same generic name. Thus
the generic name given all members of the cat tribe being Felis,
the name Felis leo designates the lion; Felis pardus, the
leopard; Felis domestica, the house cat, and so on. This seems
perfectly simple and natural now, but to understand how great a
reform the binomial nomenclature introduced we have but to
consult the work of Linnaeus's predecessors. A single
illustration will suffice. There is, for example, a kind of
grass, in referring to which the naturalist anterior to Linnaeus,
if he would be absolutely unambiguous, was obliged to use the
following descriptive formula: Gramen Xerampelino, Miliacea,
praetenuis ramosaque sparsa panicula, sive Xerampelino congener,
arvense, aestivum; gramen minutissimo semine. Linnaeus gave to
this plant the name Poa bulbosa--a name that sufficed, according
to the new system, to distinguish this from every other species
of vegetable. It does not require any special knowledge to
appreciate the advantage of such a simplification.
While visiting Paris in 1738 Linnaeus met and botanized with the
two botanists whose "natural method" of classification was later
to supplant his own "artificial system." These were Bernard and
Antoine Laurent de Jussieu. The efforts of these two scientists
were directed towards obtaining a system which should aim at
clearness, simplicity, and precision, and at the same time be
governed by the natural affinities of plants. The natural system,
as finally propounded by them, is based on the number of
cotyledons, the structure of the seed, and the insertion of the
stamens. Succeeding writers on botany have made various
modifications of this system, but nevertheless it stands as the
foundation-stone of modern botanical classification.
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