The Legacy of Greece Part 9

The early Greek literature is so scantily provided with ill.u.s.trations drawn from botanical study, that it is worth considering the remarkable comparison of generation of plants from cuttings and from seeds in the same work.

'As regards plants generated from cuttings ... that part of a branch where it was cut from a tree is placed in the earth and there rootlets are sent out. This is how it happens: The part of the plant within the soil draws up juices, swells, and develops a pneuma (p?e?a ?s?e? {pneuma ischei}), but not so the part without.

The pneuma and the juice concentrate the power of the plant below so that it becomes denser. Then the lower end erupts and gives forth tender roots. Then the plant, taking from below, draws juices from the roots and transmits them to the part above the soil which thus also swells and develops pneuma; thus the power from being diffused in the plant becomes concentrated and budding, gives forth leaves.... Cuttings, then, differ from seeds. With a seed the leaves are borne first, then the roots are sent down; with a cutting the roots form first and then the leaves.'[17]

[17] Ibid. -- 23.

But with these works of the early part of the fourth century the first stage of Greek biology reaches its finest development. Later Hippocratic treatises which deal with physiological topics are on a lower plane, and we must seek some external cause for the failure. Nor have we far to seek. This period saw the rise of a movement that had the most profound influence on every department of thought. We see the advent into the Greek world of a great intellectual movement as a result of which the department of philosophy that dealt with nature receded before Ethics. Of that intellectual revolution--perhaps the greatest the world has seen--Athens was the site and Socrates (470-399) the protagonist. With the movement itself and its characteristic fruit we are not concerned. But the great successor and pupil of its founder gives us in the _Timaeus_ a picture of the depth to which natural science can be degraded in the effort to give a specific teleological meaning to all parts of the visible Universe. The book and the picture which it draws, dark and repulsive to the mind trained in modern scientific method, enthralled the imagination of a large part of mankind for wellnigh two thousand years. Organic nature appears in this work of Plato (427-347) as the degeneration of man whom the Creator has made most perfect. The school that held this view ultimately decayed as a result of its failure to advance positive knowledge. As the centuries went by its views became further and further divorced from phenomena, and the bizarre developments of later Neoplatonism stand to this day as a warning against any system which shall neglect the investigation of nature. But in its decay Platonism dragged science down and destroyed by neglect nearly all earlier biological material. Mathematics, not being a phenomenal study, suited better the Neoplatonic mood and continued to advance, carrying astronomy with it for a while--astronomy that affected the life of man and that soon became the handmaid of astrology; medicine, too, that determined the conditions of man's life was also cherished, though often mistakenly, but pure science was doomed.

But though the ethical view of nature overwhelmed science in the end, the advent of the mighty figure of Aristotle (384-322) stayed the tide for a time. Yet the writer on Greek Biology remains at a disadvantage in contrast with the Historian of Greek Mathematics, of Greek Astronomy, or of Greek Medicine, in the scantiness of the materials for presenting an account of the development of his studies before Aristotle. The huge form of that magnificent naturalist completely overshadows Greek as it does much of later Biology.

CHARLES SINGER.

_After Aristotle_

All Aristotle's surviving biological works refer primarily to the animal creation. His work on plants is lost or rather has survived as the merest corrupted fragment. We are fortunate, however, in the possession of a couple of complete works by his pupil and successor Theophrastus (372-287), which may not only be taken to represent the Aristotelian att.i.tude towards the plant world, but also give us an inkling of the general state of biological science in the generation which succeeded the master.

[Ill.u.s.tration: Fig. 7. ARISTOTLE From HERCULANEUM Probably work of fourth century B. C.]

These treatises of Theophrastus are in many respects the most complete and orderly of all ancient biological works that have reached our time.

They give an idea of the kind of interest that the working scientist of that day could develop when inspired rather by the genius of a great teacher than by the power of his own thoughts. Theophrastus is a pedestrian where Aristotle is a creature of wings, he is in a relation to the master of the same order that the morphologists of the second half of the nineteenth century were to Darwin. For a couple of generations after the appearance of the _Origin of Species_ in 1859 the industry and ability of naturalists all over the world were occupied in working out in detail the structure and mode of life of living things on the basis of the Evolutionary philosophy. Nearly all the work on morphology and much of that on physiology since his time might be treated as a commentary on the works of Darwin. These volumes of Theophrastus give the same impression. They represent the remains--alas, almost the only biological remains--of a school working under the impulse of a great idea and spurred by the memory of a great teacher. As such they afford a parallel to much scientific work of our own day, produced by men without genius save that provided by a vision and a hope and an ideal. Of such men it is impossible to write as of Aristotle.

Their lives are summed up by their actual achievement, and since Theophrastus is an orderly writer whose works have descended to us in good state, he is a very suitable instance of the actual standard of achievement of ancient biology. 'Without vision the people perish' and the very breath of life of science is drawn, and can only be drawn, from that very small band of prophets who from time to time, during the ages, have provided the great generalizations and the great ideals. In this light let us examine the work of Theophrastus.

In the absence of any adequate system of cla.s.sification, almost all botany until the seventeenth century consisted mainly of descriptions of species. To describe accurately a leaf or a root in the language in ordinary use would often take pages. Modern botanists have invented an elaborate terminology which, however hideous to eye and ear, has the crowning merit of helping to abbreviate scientific literature. Botanical writers previous to the seventeenth century were substantially without this special mode of expression. It is partly to this lack that we owe the persistent attempts throughout the centuries to represent plants pictorially in herbals, ma.n.u.script and printed, and thus the possibility of an adequate history of plant ill.u.s.tration.

Theophrastus seems to have felt acutely the need of botanical terms, and there are cases in which he seeks to give a special technical meaning to words in more or less current use. Among such words are _carpos_ = fruit, _pericarpion_ = seed vessel = pericarp, and _metra_, the word used by him for the central core of any stem whether formed of wood, pith, or other substance. It is from the usage of Theophrastus that the exact definition of fruit and pericarp has come down to us.[18]

We may easily discern also the purpose for which he introduces into botany the term _metra_, a word meaning primarily the _womb_, and the vacancy in the Greek language which it was made to fill. '_Metra_,' he says, 'is that which is in the middle of the wood, being third in order from the bark and [thus] like to the marrow in bones. Some call it the _heart_ (?a?d?a? {kardian}), others the _inside_ (e?te??????

{enterionen}), yet others call only the innermost part of the metra itself the heart, while others again call this _marrow_.'[19] He is thus inventing a word to cover all the different kinds of core and importing it from another study. This is the method of modern scientific nomenclature which hardly existed for botanists even as late as the sixteenth century of our era. The real foundations of our modern nomenclature were laid in the later sixteenth and in the seventeenth century by Cesalpino and Joachim Jung.

[18] It is possible that Theophrastus derived the word pericarp from Aristotle. Cp. _De anima_, ii. 1, 412 b 2. In the pa.s.sage t? f?????

pe???a?p??? s?epasa, t? de pe???a?p??? ?a?p?? {to phyllon perikarpiou skepasma, to de perikarpion karpou}, in the _De anima_ the word does not, however, seem to have the full technical force that Theophrastus gives to it.

[19] _Historia plantarum_, i. 2, vi.

Theophrastus understood the value of developmental study, a conception derived from his master. 'A plant', he says, 'has power of germination in all its parts, for it has life in them all, wherefore we should regard them not for what they are but for what they are becoming.'[20]

The various modes of plant reproduction are correctly distinguished in a way that pa.s.ses beyond the only surviving earlier treatise that deals in detail with the subject, the Hippocratic work _On generation_. 'The manner of generation of trees and plants are these: spontaneous, from a seed, from a root, from a piece torn off, from a branch or twig, from the trunk itself, or from pieces of the wood cut up small.'[21] The marvel of germination must have awakened admiration from a very early date. We have already seen it occupying a more ancient author, and it had also been one of the chief preoccupations of Aristotle. It is thus not remarkable that the process should impress Theophrastus, who has left on record his views on the formation of the plant from the seed.

[20] _Ibid._ i. 1, iv.

[21] _Historia plantarum_, ii. 1, i.

'Some germinate, root and leaves, from the same point, some separately from either end of the seed. Thus wheat, barley, spelt, and all such cereals [germinate] from either end, corresponding to the position [of the seed] in the ear, the root from the stout lower part, the shoot from the upper; but the two, root and stem, form a single continuous whole. The bean and other leguminous plants are not so, but in them root and stem are from the same point, namely, their place of attachment to the pod, where, it is plain, they have their origin. In some cases there is a process, as in beans, chick peas, and especially lupines, from which the root grows downward, the leaf and stem upward.... In certain trees the bud first germinates within the seed, and, as it increases in size, the seeds split--all such seeds are, as it were, in two halves; again, all those of leguminous plants have plainly two lobes and are double--and then the root is immediately thrust out. But in cereals, the seeds being in one piece, this does not happen, but the root grows a little before [the shoot].

'Barley and wheat come up monophyllous, but peas, beans, and chick peas polyphyllous. All leguminous plants have a single woody root, from which grow slender side roots ... but wheat, barley, and the other cereals have numerous slender roots by which they are matted together.... There is a contrast between these two kinds; the leguminous plants have a single root and have many side-growths above from the [single] stem ... while the cereals have many roots and send up many shoots, but these have no side-shoots.'[22]

[22] _Historia plantarum_, viii. 1, i.

There can be no doubt that here is a piece of minute observation on the behaviour of germinating seeds. The distinction between dicotyledons and monocotyledons is accurately set forth, though the stress is laid not so much on the cotyledonous character of the seed as on the relation of root and shoot. In the dicotyledons root and shoot are represented as springing from the same point, and in monocotyledons from opposite poles in the seed.

No further effective work was done on the germinating seed until the invention of the microscope, and the appearance of the work of Highmore (1613-85),[23] and the much more searching investigations of Malpighi (1628-94)[24] and Grew (1641-1712)[25] after the middle of the seventeenth century. The observations of Theophrastus are, however, so accurate, so lucid, and so complete that they might well be used as legends for the plates of these writers two thousand years after him.

[23] Nathaniel Highmore, _A History of Generation_, London, 1651.

[24] Marcello Malpighi, _Anatome plantarum_, London, 1675.

[25] Nehemiah Grew, _Anatomy of Vegetables begun_, London, 1672.

Much has been written as to the knowledge of the s.e.x of plants among the ancients. It may be stated that of the s.e.xual elements of the flower no ancient writer had any clear idea. Nevertheless, s.e.x is often attributed to plants, and the simile of the _Loves of Plants_ enters into works of the poets. Plants are frequently described as male and female in ancient biological writings also, and Pliny goes so far as to say that some students considered that all herbs and trees were s.e.xual.[26] Yet when such pa.s.sages can be tested it will be found that these so-called males and females are usually different species. In a few cases a sterile variety is described as the male and a fertile as the female. In a small residuum of cases dicious plants or flowers are regarded as male and female, but with no real comprehension of the s.e.xual nature of the flowers. There remain the palms, in which the knowledge of plant s.e.x had advanced a trifle farther. 'With dates', says Theophrastus, 'the males should be brought to the females; for the males make the fruit persist and ripen, and this some call by a.n.a.logy _to use the wild fig_ (?????a?e?? {olynthazein}).[27] The process is thus: when the male is in the flower they at once cut off the spathe with the flower and shake the bloom, with its flower and dust, over the fruit of the female, and, if it is thus treated, it retains the fruit and does not shed it.'[28] The fertilizing character of the spathe of the male date palm was familiar in Babylon from a very early date. It is recorded by Herodotus[29] and is represented by a frequent symbol on the a.s.syrian monuments.

[26] Pliny, _Naturalis historia_, xiii. 4.

[27] The curious word ?????a?e?? {olynthazein}, here translated _to use the wild fig_, is from ??????? {olynthos}, a kind of wild fig which seldom ripens. The special meaning here given to the word is explained in another work of Theophrastus, _De causis plantarum_, ii. 9, xv. After describing caprification in figs, he says t? de ep?

t?? f??????? s?a???? ?? ta?t?? e?, e?e? de t??a ????t?ta t??t?

d?' ? ?a???s?? ?????a?e?? a?t??? {to de epi ton phoinikon symbainon ou tauton men, echei de tina h.o.m.oioteta touto di' ho kalousin olynthazein autous} 'The same thing is not done with dates, but something a.n.a.logous to it, whence this is called ?????a?e??'

{olynthazein'}.

[28] _Historia plantarum_, ii. 8, iv.

[29] Herodotus i. 193.

The comparison of the fertilization of the date palm to the use of the wild fig refers to the practice of Caprification. Theophrastus tells us that there are certain trees, the fig among them, which are apt to shed their fruit prematurely. To remedy this 'the device adopted is caprification. Gall insects come out of the wild figs which are hanging there, eat the tops of the cultivated figs, and so make them swell'.[30]

These gall-insects 'are engendered from the seeds'.[31] Theophrastus distinguished between the process as applied to the fig and the date, observing that 'in both [fig and date] the male aids the female--for they call the fruit-bearing [palm] _female_--but whilst in the one there is a union of the two s.e.xes, in the other things are different'.[32]

[30] _Historia plantarum_, ii. 8, i.

[31] _Ibid._ ii. 8, ii.

[32] _Historia plantarum_, ii. 8, iv.

Theophrastus was not very successful in distinguishing the nature of the primary elements of plants, though he was able to separate root, stem, leaf, stipule, and flower on morphological as well as to a limited extent on physiological grounds. For the root he adopts the familiar definition, the only one possible before the rise of chemistry, that it 'is that by which the plant draws up nourishment',[33] a description that applies to the account given by the pre-Aristotelian author of the work pe?? ????? {peri gones}, _On generation_. But Theophrastus shows by many examples that he is capable of following out morphological h.o.m.ologies. Thus he knows that the ivy regularly puts forth roots from the shoots between the leaves, by means of which it gets hold of trees and walls,[34] that the mistletoe will not sprout except on the bark of living trees into which it strikes its roots, and that the very peculiar formation of the mangrove tree is to be explained by the fact that 'this plant sends out roots from the shoots till it has hold on the ground and roots again: and so there comes to be a continuous circle of roots round the tree, not connected with the main stem, but at a distance from it'.[35] He does not succeed, however, in distinguishing the real nature of such structures as bulbs, rhizomes, and tubers, but regards them all as roots. Nor is he more successful in his discussion of the nature of stems. As to leaves, he is more definite and satisfactory, though wholly in the dark as to their function; he is quite clear that the pinnate leaf of the rowan tree, for instance, is a leaf and not a branch.

[33] _Ibid._ i. 1, ix.

[34] _Ibid._ iii. 18, x.

[35] _De causis plantarum_, ii. 23.

Notwithstanding his lack of insight as to the nature of s.e.x in flowers, he attains to an approximately correct idea of the relation of flower and fruit. Some plants, he says, 'have [the flower] around the fruit itself as vine and olive; [the flowers] of the latter, when they drop, look as though they had a hole through them, and this is taken for a sign that it has blossomed well; for if [the flower] is burnt up or sodden, the fruit falls with it, and so it does not become pierced. Most flowers have the fruit case in the middle, or it may be the flower is on the top of the pericarp as in pomegranate, apple, pear, plum, and myrtle ... for these have their seeds below the flower.... In some cases again the flower is on top of the seeds themselves as in ... all thistle-like plants'.[36] Thus Theophrastus has succeeded in distinguishing between the hypogynous, perigynous, and epigynous types of flower, and has almost come to regard its relation to the fruit as the essential floral element.

[36] _Historia plantarum_, i. 13, iii.

[Ill.u.s.tration: Fig. 8. THEOPHRASTUS From VILLA ALBANI Copy (second century A. D.?) of earlier work]

Theophrastus has a perfectly clear idea of plant distribution as dependent on soil and climate, and at times seems to be on the point of pa.s.sing from a statement of climatic distribution into one of real geographical regions. The general question of plant distribution long remained at, if it did not recede from, the position where he left it.

The usefulness of the ma.n.u.script and early printed herbals in the West was for centuries marred by the retention of plant descriptions prepared for the Greek East and Latin South, and these works were saved from complete ineffectiveness only by an occasional appeal to nature.

With the death of Theophrastus about 287 B. C. pure biological science substantially disappears from the Greek world, and we get the same type of deterioration that is later encountered in other scientific departments. Science ceases to have the motive of the desire to know, and becomes an applied study, subservient to the practical arts. It is an att.i.tude from which in the end applied science itself must suffer also. Yet the centuries that follow were not without biological writers of very great ability. In the medical school of Alexandria anatomy and physiology became placed on a firm basis from about 300 B. C., but always in the position subordinate to medicine that they have since occupied. Two great names of that school, Herophilus and Erasistratus, we must consider elsewhere.[37] Their works have disappeared and we have the merest fragments of them. In the last pre-Christian and the first two post-Christian centuries, however, there were several writers, portions of whose works have survived and are of great biological importance. Among them we include Crateuas, a botanical writer and ill.u.s.trator, who greatly developed, if he did not actually introduce, the method of representing plants systematically by ill.u.s.tration rather than by description. This method, important still, was even more important when there was no proper system of botanical nomenclature.

Crateuas by his paintings of plants, copies of which have not improbably descended to our time, began a tradition which, fixed about the fifth century, remained almost rigid until the re-discovery of nature in the sixteenth. He was physician to Mithridates VI Eupator (120-63 B. C.), but his work was well known and appreciated at Rome, which became the place of resort for Greek talent.[38]