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 variably helpful in difficult or obscure cases as we might reasonably expect, but much may be hoped from further experience.

5. The systematic clinical investigation of the blood on scientific lines is essentially modern, and is still making steady progress. It is not only of incalculable service in recognising changes in the blood itself, but also in the diagnosis of important diseases or conditions of a general or local nature, in which the blood is involved. For this purpose not only is the microscope in constant demand, with or without the help of different staining processes, but special instruments or apparatus are called into requisition for various objects, some of which are well within the scope of the ordinary practitioner; but others require the aid of an expert in this branch of pathological science. Chemical testing and the spectroscope are also sometimes of service. With this extensive subject I do not propose to deal further at present.

As a practitioner Harvey does not seem to have been held in high esteem by his contemporaries, if Aubrey is to be believed, for he writes: "Though all of his profession would allow him to be an excellent anatomist, I never heard of any that admired his therapeutic ways. I knew several practitioners that would not have given threepence for one of his bills." Harvey recognised the value of