Stensen had been at the University scarcely two years when the city of Copenhagen was besieged by the Swedes. Professor Lutz, of the University of St. Louis, who has recently written {142} an article on Stensen, which appeared in the _Medical Library and Historical Journal_ for July, 1904, says of this period: 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.