A regiment of students numbering two hundred and sixty-six, called "the black coats" on account of their dark clothes, was formed for the defence of the city; upon its roster we find the name of young Steno. During the day they were at work mending the ramparts, and the nights were spent in repelling the attacks of the enemy. In the course of this long siege, the city was compelled to cope with a more formidable enemy than the Swedes--famine with all its horrors--before relief came in the shape of provisions and reinforcements furnished by the Dutch fleet. Throughout these turbulent days the student soldiers rendered valuable services to their country, and though it be true that "inter arma silent musae"--"the war gods do not favor the muses"--it appears nevertheless that Steno attended the lectures and dissections which were conducted by the teachers in the intervals when the student were not on duty.
After some three years spent at the University of Copenhagen, Stensen, as was the custom of the times, went to pursue his post-graduate studies in a foreign university. Bartholini furnished him with a letter of recommendation to Professor Blasius, who was teaching anatomy at Amsterdam in Holland. Amsterdam had become famous during the seventeenth century for the very practical character of its anatomical teaching. As the result of the cordial commendation of Bartholini, Stensen became an inmate of the house of Professor Blasius, and was given [{143}] special opportunities to pursue his anatomical studies for himself. He had been but a very short time at Amsterdam, when he made the discovery to which his name has ever since been attached, that of the duct of the parotid gland. Stensen's discovery was made while he was dissecting the head of a sheep. He found shortly afterwards, however, that the canal could be demonstrated to exist in the dog, though it was not so large a structure. Blasius seems to have been rather annoyed at the fact that a student, just beginning work with him, should make so important a discovery, and wished to claim the honor of it for himself. There is no doubt, however, now, notwithstanding the discussion over the priority of the discovery which took place at the time, that Stensen was the first to make this important observation.
Not long before, Wharton, an English observer, had demonstrated the existence of a canal leading from the submaxillary gland into the mouth. This might have been expected to lead to the discovery of other glandular ducts, but so far had not. As a matter of fact, the function of the parotid gland was not well understood at this time. During the discussion as to priority of discovery, Steno pointed out one fact which he very properly considers as the most conclusive proof that Blasius did not discover the duct of the gland. He says: "Blasius shows plainly in his treatise 'De Medicina Generali' that he has never sought for the duct, for he does not assign [{144}] to it either the proper point of beginning or ending, and assigns to the parotid gland itself so unworthy a function as that of furnishing warmth to the ear, so that if I were not perfectly sure of having once shown him the duct myself, I should be tempted to say that he had never seen it."
Bartholini settled the controversy, and at the same time removed any discouragement that might have arisen in his young pupil's mind, by writing to him:--
Your assiduity in investigating the secrets of the human body, as well as your fortunate discoveries, are highly praised by the learned of your country. The fatherland congratulates itself upon such a citizen, I upon such a pupil, through whose efforts anatomy makes daily progress, and our lympathic vessels are traced out more and more. You divide honors with Wharton, since you have added to his internal duct an external one, and have thereby discovered the sources of the saliva concerning which many have hitherto dreamed much, but which no one has (permit the expression) pointed out with the finger. Continue, my Steno, to follow the path to immortal glory which true anatomy holds out to you.
Under the stimulus of such encouragement, it is no wonder that Stensen continued his original work with eminent success. He published an extensive article on the glands of the eye and the vessels of the nose.
Bartholini wrote to him again: "Your fame is growing from day to day, for your pen and your sharp eye know no rest." Later he wrote [{145}] again: "You may count upon the favor of the king as well as upon the applause of the learned." After three years at the University of Amsterdam, Steno returned to Copenhagen, where he published his "Anatomical Observations Concerning the Muscles and Glands." It was in this book that he announced his persuasion that the heart was a muscle. As he said himself, "the heart has been considered the seat of natural warmth, the throne of the soul; but if you examine it more closely, it turns out to be nothing but a muscle. The men of the past would not have been so grossly mistaken with regard to it, had they not preferred their imaginary theories to the results of the simple observation of nature." It is easy to understand that this observation created a very great sensation. It had much to do with overthrowing certain theoretic systems of medicine, and nearly a century later the distinguished physiologist, Haller, did not hesitate to proclaim the volume in which it occurs, as a "golden book."
Stensen's studies in anatomy stamp him as an original genius of a high order, and this is all the more remarkable because his career occurs just in those years when there were distinguished discoverers in anatomy in every country in Europe. When Stensen began his work in anatomy, Harvey was still alive. The elder Bartholini, the first who ever established an anatomical museum, was another of his contemporaries. Among the names of distinguished anatomists [{146}] with whom Stensen was brought intimately 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.