FROM the death of Hippocrates about the year 375 B.C. till the founding of the Alexandrian School, the physicians were engrossed largely in speculative views, and not much real progress was made, except in the matter of elaborating the humoral pathology. Only three or four men of the first rank stand out in this period: Diocles the Carystian, "both in time and reputation next and second to Hippocrates" (Pliny), a keen anatomist and an encyclopaedic writer; but only scanty fragments of his work remain. In some ways the most important member of this group was Praxagoras, a native of Cos, about 340 B.C. Aristotle, you remember, made no essential distinction between arteries and veins, both of which he held to contain blood: Praxagoras recognized that the pulsation was only in the arteries, and maintained that only the veins contained blood, and the arteries air. As a rule the arteries are empty after death, and Praxagoras believed that they were filled with an aeriform fluid, a sort of pneuma, which was responsible for their pulsation. The word arteria, which had already been applied to the trachea, as an air-containing tube, was then attached to the arteries; on account of the rough and uneven character of its walls the trachea was then called the arteria tracheia, or the rough air-tube.(31a) We call it simply the trachea, but in French the word trachee-artere is still used.

Praxagoras was one of the first to make an exhaustive study of the pulse, and he must have been a man of considerable clinical acumen, as well as boldness, to recommend in obstruction of the bowels the opening of the abdomen, removal of the obstructed portion and uniting the ends of the intestine by sutures.

After the death of Alexander, Egypt fell into the hands of his famous general, Ptolemy, under whose care the city became one of the most important on the Mediterranean. He founded and maintained a museum, an establishment that corresponded very much to a modern university, for the study of literature, science and the arts. Under his successors, particularly the third Ptolemy, the museum developed, more especially the library, which contained more than half a million volumes. The teachers were drawn from all centres, and the names of the great Alexandrians are among the most famous in the history of human knowledge, including such men as Archimedes, Euclid, Strabo and Ptolemy.

In mechanics and physics, astronomy, mathematics and optics, the work of the Alexandrians constitutes the basis of a large part of our modern knowledge. The school-boy of today—or at any rate of my day—studies the identical problems that were set by Euclid 300 B.C., and the student of physics still turns to Archimedes and Heron, and the astronomer to Eratosthenes and Hipparchus. To those of you who wish to get a brief review of the state of science in the Alexandrian School I would recommend the chapter in Vol. I of Dannemann's history.(31)

Of special interest to us in Alexandria is the growth of the first great medical school of antiquity. Could we have visited the famous museum about 300 B.C., we should have found a medical school in full operation, with extensive laboratories, libraries and clinics. Here for the first time the study of the structure of the human body reached its full development, till then barred everywhere by religious prejudice; but full permission was given by the Ptolemies to perform human dissection and, if we may credit some authors, even vivisection. The original writings of the chief men of this school have not been preserved, but there is a possibility that any day a papyrus maybe found which will supplement the scrappy and imperfect knowledge afforded us by Pliny, Celsus and Galen. The two most distinguished names are Herophilus—who, Pliny says, has the honor of being the first physician "who searched into the causes of disease"—and Erasistratus.

Herophilus, ille anatomicorum coryphaeus, as Vesalius calls him, was a pupil of Praxagoras, and his name is still in everyday use by medical students, attached to the torcular Herophili. Anatomy practically dates from these Alexandrines, who described the valves of the heart, the duodenum, and many of the important parts of the brain; they recognized the true significance of the nerves (which before their day had been confounded with the tendons), distinguished between motor and sensory nerves, and regarded the brain as the seat of the perceptive faculties and voluntary action. Herophilus counted the pulse, using the water-clock for the purpose, and made many subtle analyses of its rate and rhythm; and, influenced by the musical theories of the period, he built up a rhythmical pulse lore which continued in medicine until recent times. He was a skilful practitioner and to him is ascribed the statement that drugs are the hands of the gods. There is a very modern flavor to his oft-quoted expression that the best physician was the man who was able to distinguish between the possible and the impossible.

Erasistratus elaborated the view of the pneuma, one form of which he believed came from the inspired air, and passed to the left side of the heart and to the arteries of the body. It was the cause of the heart-beat and the source of the innate heat of the body, and it maintained the processes of digestion and nutrition. This was the vital spirit; the animal spirit was elaborated in the brain, chiefly in the ventricles, and sent by the nerves to all parts of the body, endowing the individual with life and perception and motion. In this way a great division was made between the two functions of the body, and two sets of organs: in the vascular system, the heart and arteries and abdominal organs, life was controlled by the vital spirits; on the other hand, in the nervous system were elaborated the animal spirits, controlling motion, sensation and the various special senses. These views on the vital and animal spirits held unquestioned sway until well into the eighteenth century, and we still, in a measure, express the views of the great Alexandrian when we speak of "high" or "low" spirits.