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 correctness of Daremberg's statement that Galen was the leader of the most advanced school of experimentation:—

The more strongly the thorax, in its exertion of a compressing force, tends to drive the blood (out of the heart), the more tightly do these membranes (the sigmoid valves) close the opening. Invested in a circular manner from within outward, extending throughout the entire circumference of the interior of the vessel, these membranous valves are, each one of them, so accurately patterned and so perfectly fitted that when they are put upon the stretch by the column of blood, they constitute a single large membrane which closes (watertight) the orifice. Pushed back by the return flow of the blood, they fall back against the inner surface of the vein, and permit an easy passage of the blood through the amply dilated orifice (which they, an instant before, closed so perfectly).

(Translated from Book VI., Chapter XI., of Daremberg's French version of the works of Galen.)

In his comments upon the account of the sigmoid valves which I have just quoted, Daremberg says that the description of these structures given by Erasistratus at least four hundred years earlier is admitted by Galen to be so correct that it would scarcely be possible to furnish a better one.

Galen's Remarks upon the Subject of Diagnosis.—In the treatise entitled "On the parts of the Body Affected" (Book II., Chapter X.) Galen gives the following advice with regard to the method which it is desirable to adopt when one wishes to ascertain which part or organ is affected, what is the nature of the disease there located, and whether it is primary in its nature or secondary to some affection of earlier development:—

It should have been the special duty of Archigenes, who appeared on the scene next in order after a series of the most illustrious physicians, to infuse more light into medical teaching. Unfortu-**