"4. He watched the development of seeds and was able to some extent to distinguish between dicotyledons and monocotyledons.

5. He established a relationship between structure and habits, and approaches the conception of geographical distribution.

6. He saw the need for a general classification of plants and made some attempt at a system, though he failed to produce one which was in fact workable.

"7. He perceived a general relation between structure and function in plants, and thus laid the basis of scientific botany."

IV. PROGRESS IN ANATOMY AND

I

MEDICINE

T IS by an easy transition that we turn from biology to medicine, from pure

science inspired by the sheer desire to know and account for living organisms, to the healing art, which may be also scientific, though led by practical beneficent intent. The transition is the easier because we are in the later fourth and the third centuries before Christ, the most brilliant scientific age of Greece, though Aristotle lived no longer. Medicine in the Alexandrian school, led by Herophilus and Erasistratus, was supported by the now veritable sciences of anatomy and physiology.

And of their works only scattered fragments have survived! Admirable as these men were, we must remember that we are not engaged upon a history of Greek medicine or biology, but are thinking of the value to the moderns of what the Greeks accomplished. Therefore we must occupy ourselves chiefly with those

works which have survived, as the direct vehicles of the ancient heritage; and such, above all, are the works of the Hippocratics, of Aristotle and of Galen. Hence we pass by many men, brave and good, with but slight mention. Our present task is to trace the currents of medicine and its supporting sciences through the later Greek and best Roman periods till they are gathered up into the encyclopaedic system of Galen in the latter part of the second century after Christ."

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In the third century before Christ, Alexandria presented such facilities and incentives for study and investigation as had never before been brought together. The first Ptolemies formed a great library covering all subjects of study, and established zoölogical parks and botanical gardens. Their munificence enabled scholars and men of science to pursue their studies; and mathematics, astronomy and physics flourished, as well as history, philology, and poetry. There were hospitals for the treatment and observation of diseases, and for perhaps a century human bodies were methodically dissected. Possibly the Egyptian custom of opening the body for embalming had dispelled the Greek aversion to mutilation of the

dead. But dissection of human bodies appears to have been stopped before the close of the second century before Christ, though the dissection of dead and living animals continued.

Herophilus and Erasistratus belong to the Alexandrian period, though only the former is known to have worked in Alexandria. They were born about the year three hundred. The reputation of Herophilus has come down to us less assaulted than that of Erasistratus, whom Galen hated for his alleged mechanical view of the action of the human organs.

Herophilus was at all events the more deferential in his treatment of Hippocrates, and this was to be the test of orthodoxy in the Greco-Roman medical tradition. He did not dispute the conception of the four humors, but preferred to think of four faculties as moving the human organism, to wit, the nourishing faculty of the liver and digestive organs, the warming power of the heart, the thinking faculty of the brain, and the perceptive faculty of the nerves. Above all, this man relied upon clinical observation and the results of his dissections. He appears to have been the first to have worked through the through the entire human anatomy. He discerned the connection be

tween the brain and spinal cord and the nerves which proceeded from these centres; also the connection of the digestive system with the lacteals; and by the aid of the clepsydra he made a study of pulse variations as a gauge of the patient's condition. Realizing the dangers of medical theory, he fell back upon the sound clinical methods of Hippocrates; and like the master, avoided the finely drawn distinctions of unproved diagnoses. His own further experience and his greater knowledge of anatomy were brought to bear upon his treatment of diseases, while he also made improvements in surgery and obstetrics. A great and admirable figure this Herophilus.

Less conservative and Hippocratic was Erasistratus (also a great practitioner), who would have nothing to do with the four humors or four anything. Believing that a general knowledge of the human body and its functioning in health was not necessarily of practical use to the physician, he tended to specialize in his own anatomical researches, which were, however, brilliant in result. He gave a better description of the liver and its gall ducts, and for the first time gave a correct description of the heart. He advanced the knowledge of the