mately in contact during the course of
his studies in Holland, France and Italy are those of Swammerdam, Van
Horne, and Malpighi. There is no doubt that his intercourse with such
men sharpened his own intellectual activity, and increased his
enthusiasm for original investigation in contradistinction to the mere
accumulation of information.

His contemporaries, indeed, exhausted most of the adjectives of the
Latin language in trying to express their appreciation of his acuity
of observation. He was spoken of as _oculatissimus_--that is, as
being all eyes, _subtilissimus, acutissimus, sagacissimus_ in his
knowledge of the human body, and as the most perspicacious anatomist
of the time. Leibnitz and Haller were in accord in considering him one
of the greatest of anatomists. In later years this admiration for
Stensen's genius has not been less enthusiastically expressed. Haeser,
in his "History of Medicine," the third edition of which appeared at
Jena in 1879, says: "Among the greatest anatomists of the seventeenth
century belongs Nicholas Steno, the most distinguished pupil of Thomas
Bartholini. Steno was rightly considered in his own time as one of the
greatest of anatomical discoverers. There is scarcely any part of the
human body the knowledge of which was not rendered more complete by
his investigations."

The most valuable discovery made by Stensen was undoubtedly that the
heart is a muscle. It {147} must not be forgotten that in his time,
Harvey's discovery of the circulation of the blood was not yet
generally accepted; indeed, there were many who considered the theory
(as they called it) of the English investigator as one of the passing
fads of medicine. Two significant discoveries, made after Harvey,
served, however, to establish the theory of the circulation of the
blood on a firm basis and to make it a definite medical doctrine. The
most important of these was Malpighi's discovery that the
capillaries--that is, the minute vessels at the end of the arterial
tree on the surface of the body and in various organs--served as the
direct connexion between the veins and the arteries. This demonstrated
just how the blood passed from the arterial to the venous system.
Scarcely less important, however, for the confirmation of Harvey's
teaching was Stensen's demonstration of the muscular character of the
tissue of the heart.

Some of his observations upon muscles are extremely interesting, and,
though he made many mistak