Part 10 (1/2)

[37] See the companion chapter on _Greek Medicine_.

[38] The surviving fragments of the works of Crateuas have recently been printed by M. Wellmann as an appendix to the text of Dioscorides, _De materia medica_, 3 vols., Berlin, 1906-17, iii. pp.

144-6. The source and fate of his plant drawings are discussed in the same author's _Krateuas_, Berlin, 1897.

Celsus, who flourished about 20 B. C., wrote an excellent work on medicine, but gives all too little glimpse of anatomy and physiology.

Rufus of Ephesus, however, in the next century practised dissection of apes and other animals. He described the decussation of the optic nerves and the capsule of the crystalline lens, and gave the first clear description that has survived of the structure of the eye. He regarded the nerves as originating from the brain, and distinguished between nerves of motion and of sensation. He described the oviduct of the sheep and rightly held that life was possible without the spleen.

The second Christian century brings us two writers who, while scientifically inconsiderable, acted as the main carriers of such tradition of Greek biology as reached the Middle Ages, Pliny and Dioscorides. Pliny (A. D. 23-79), though a Latin, owes almost everything of value in his encyclopaedia to Greek writings. In his _Natural History_ we have a collection of current views on the nature, origin, and uses of plants and animals such as we might expect from an intelligent, industrious, and honest member of the landed cla.s.s who was devoid of critical or special scientific skill. Scientifically the work is contemptible, but it demands mention in any study of the legacy of Greece, since it was, for centuries, a main conduit of the ancient teaching and observations on natural history. Read throughout the ages, alike in the darkest as in the more enlightened periods, copied and recopied, translated, commented on, extracted and abridged, a large part of Pliny's work has gradually pa.s.sed into folk-keeping, so that through its agency the gipsy fortune-teller of to-day is still reciting garbled versions of the formulae of Aristotle and Hippocrates of two and a half millennia ago.

The fate of Dioscorides (flourished A. D. 60) has been not dissimilar.

His work _On Materia Medica_ consists of a series of short accounts of plants, arranged almost without reference to the nature of the plants themselves, but quite invaluable for its terse and striking descriptions which often include habits and habitats. Its history has shown it to be one of the most influential botanical treatises ever penned. It provided most of the little botanical knowledge that reached the Middle Ages. It furnished the chief stimulus to botanical research at the time of the Renaissance. It has decided the general form of every modern pharmacopia. It has practically determined modern plant nomenclature both popular and scientific.

Translated into nearly every language from Anglo-Saxon and Bohemian to Arabic and Hebrew, appearing both abstracted and in full in innumerable beautifully illuminated ma.n.u.scripts, some of which are still among the fairest treasures of the great national libraries, Dioscorides, the drug-monger, appealed to scholasticized minds for centuries. The frequency with which fragments of him are encountered in papyri shows how popular his work was in Egypt in the third and fourth centuries. One of the earliest datable Greek codices in existence is a glorious volume of Dioscorides written in capitals,[39] thought worthy to form a wedding gift for a lady who was the daughter of one Roman emperor and the betrothed of a second.[40] The ill.u.s.trations of this fifth-century ma.n.u.script are a very valuable monument for the history of art and the chief adornment of what was once the Royal Library at Vienna[41] (figs.

9-10). Ill.u.s.trated Latin translations of Dioscorides were in use in the time of Ca.s.siodorus (490-585). A work based on it, similarly ill.u.s.trated, but bearing the name of Apuleius, is among the most frequent of mediaeval botanical doc.u.ments and the earliest surviving specimen is contemporary with Ca.s.siodorus himself.[42] After the revival of learning Dioscorides continued to attract an immense amount of philological and botanical ability, and scores of editions of his works, many of them n.o.bly ill.u.s.trated, poured out of the presses of the sixteenth and seventeenth centuries.

[Ill.u.s.tration: Fig. 9 S?G??S ???F???S {SOGKOS TRYPHEROS} = _Crepis paludosa_, _Mn._]

[Ill.u.s.tration: Fig. 10 G??????? {GERANION} = _Geranium pyrenaic.u.m_, _L._

Fifth-century drawings from JULIANA ANICIA M.S., copied from originals of first century B. C. (?)]

[39] The ma.n.u.script in question is Med. Graec. 1 at what was the Royal Library at Vienna. It is known as the _Constantinopolita.n.u.s_.

After the war it was taken to St. Mark's at Venice, but either has been or is about to be restored to Vienna. A facsimile of this grand ma.n.u.script was published by Sijthoff, Leyden, 1906.

[40] The lady in question was Juliana Anicia, daughter of Anicius Olybrius, Emperor of the West in 472, and his wife Placidia, daughter of Valentinian III. Juliana was betrothed in 479 by the Eastern Emperor Zeno to Theodoric the Ostrogoth, but was married, probably in 487 when the ma.n.u.script was presented to her, to Areobindus, a high military officer under the Byzantine Emperor Anastasius.

[41] The importance of this ma.n.u.script as well as the position of Dioscorides as medical botanist is discussed by Charles Singer in an article 'Greek Biology and the Rise of Modern Biology', _Studies in the History and Method of Science_, vol. ii, Oxford, 1921.

[42] This ma.n.u.script is at the University Library at Leyden, where it is numbered Voss Q 9.

But the greatest biologist of the late Greek period, and indeed one of the greatest biologists of all time, was Claudius Galen of Pergamon (A.

D. 131-201). Galen devoted himself to medicine from an early age, and in his twenty-first year we hear of him studying anatomy at Smyrna under Pelops. With the object of extending his knowledge of drugs he early made long journeys to Asia Minor. Later he proceeded to Alexandria, where he improved his anatomical equipment, and here, he tells us, he examined a human skeleton. It is indeed probable that his direct practical acquaintance with human anatomy was limited to the skeleton and that dissection of the human body was no longer carried on at Alexandria in his time. Thus his physiology and anatomy had to be derived mainly from animal sources. He is the most voluminous of all ancient scientific writers and one of the most voluminous writers of antiquity in any department. We are not here concerned with the medical material which mainly fills these huge volumes, but only with the physiological views which not only prevailed in medicine until Harvey and after, but also governed for fifteen hundred years alike the scientific and the popular ideas on the nature and workings of the animal body, and have for centuries been embedded in our speech. A knowledge of these physiological views of Galen is necessary for any understanding of the history of biology and illuminates many literary allusions of the Middle Ages and Renaissance.

Between the foundation of the Alexandrian school and the time of Galen, medicine was divided among a great number of sects. Galen was an eclectic and took portions of his teaching from many of these schools, but he was also a naturalist of great ability and industry, and knew well the value of the experimental way. Yet he was a somewhat windy philosopher and, priding himself on his philosophic powers, did not hesitate to draw conclusions from evidence which was by no means always adequate. The physiological system that he thus succeeded in building up we may now briefly consider (fig. 11).

[Ill.u.s.tration: FIG. 11. Ill.u.s.trating Galen's physiological teaching.]

The basic principle of life, in the Galenic physiology, is a _spirit_, _anima_ or _pneuma_, drawn from the general world-soul in the act of respiration. It enters the body through the _rough artery_ (t?a?e?a a?t???a {tracheia arteria}, _arteria aspera_ of mediaeval notation), the organ known to our nomenclature as the trachea. From this trachea the pneuma pa.s.ses to the lung and then, through the _vein-like artery_ (a?t???a f?e?d?? {arteria phlebodes}, _arteria venalis_ of mediaeval writers, the pulmonary vein of our nomenclature), to the left ventricle.

Here it will be best to leave it for a moment and trace the vascular system along a different route.

Ingested food, pa.s.sing down the alimentary tract, was absorbed as chyle from the intestine, collected by the portal vessel, and conveyed by it to the liver. That organ, the site of the innate heat in Galen's view, had the power of elaborating the chyle into venous blood and of imbuing it with a spirit or pneuma which is innate in all living substance, so long as it remains alive, the _natural spirits_ (p?e?a f?s???? {pneuma physikon}, _spiritus naturalis_ of the mediaevals). Charged with this, and also with the nutritive material derived from the food, the venous blood is distributed by the liver through the veins which arise from it in the same way as the arteries from the heart. These veins carry nourishment and _natural spirits_ to all parts of the body. _Iecur fons venarum_, the liver as the source of the veins, remained through the centuries the watchword of the Galenic physiology. The blood was held to ebb and flow continuously in the veins during life.

Now from the liver arose one great vessel, the hepatic vein, from division of which the others were held to come off as branches. Of these branches, one, our _common vena cava_, entered the right side of the heart. For the blood that it conveyed to the heart there were two fates possible. The greater part remained awhile in the ventricle, parting with its impurities and vapours, exhalations of the organs, which were carried off by the _artery-like vein_ (f?ep? a?t????d??

{phleps arteriodes}, the mediaeval _vena arterialis_, our pulmonary artery) to the lung and then exhaled to the outer air. These impurities and vapours gave its poisonous and suffocating character to the breath.

Having parted thus with its impurities, the venous blood ebbed back again from the right ventricle into the venous system. But for a small fraction of the venous blood that entered the right ventricle another fate was reserved. This small fraction of venous blood, charged still with the _natural spirits_ derived from the liver, pa.s.sed through minute channels in the septum between the ventricles and entered the left chamber. Arrived there, it encountered the external pneuma and became thereby elaborated into a higher form of spirit, the _vital spirits_ (p?e?a ??t???? {pneuma zotikon}, _spiritus vitalis_), which is distributed together with blood by the arterial system to various parts of the body. In the arterial system it also ebbed and flowed, and might be seen and felt to pulsate there.

But among the great arterial vessels that sent forth arterial blood thus charged with vital spirits were certain vessels which ascended to the brain. Before reaching that organ they divided up into minute channels, the _rete mirabile_ (p?e?a e??st?? ?a?a {plegma megiston thauma}), and pa.s.sing into the brain became converted by the action of that organ into a yet higher type of spirits, the _animal spirits_ (p?e?a ???????

{pneuma psychikon}, _spiritus animalis_), an ethereal substance distributed to the various parts of the body by the structures known to-day as nerves, but believed then to be hollow channels. The three fundamental faculties (d??ae?? {dynameis}), the _natural_, the _vital_, and the _animal_, which brought into action the corresponding functions of the body, thus originated as an expression of the primal force or pneuma.

This physiology, we may emphasize, is not derived from an investigation of human anatomy. In the human brain there is no _rete mirabile_, though such an organ is found in the calf. In the human liver there is no _hepatic vein_, though such an organ is found in the dog. Dogs, calves, pigs, bears, and, above all, Barbary apes were freely dissected by Galen and were the creatures from which he derived his physiological ideas.