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.

(31a) Galen: De usu partium, VII, Chaps. 8-9.

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, as