The aula in which Vesalius conducted his course was built of wood and was capable of holding five hundred persons. In the centre of the room was a table under which was a receptacle containing bones and joints. An articulated skeleton was placed in an upright position at one end of the table. In this elegantly appointed room, before an audience of distinguished laymen and students, the instruction in anatomy was given. The course was a strenuous one, occupying practically the entire day for a period of three weeks, and comprising not only human but also much comparative anatomy. The vivisection of dogs, pigs, and rarely of cats, was a regular part of the course. Drawings were used to elucidate the relations between the skeleton and the soft parts; and frequently Vesalius marked the outlines of the joints upon the skin of the subject. He also marked the cranial sutures with ink. His anatomical charts were the work of his own hand; at times he drew the pictures in the presence of his audience. His dissections were made with extreme neatness and dexterity. He used but few instruments and these were of the simplest kind: knives of different shapes, hooks, cannula, catheter, sounds, bristles, hammer, saw, needles, thread and a sponge. Forceps and injection apparatus were not used; he rarely used scissors. Much of the actual separation of tissues was done by the aid of the finger-nails. A vivisection board completed the list _de instrumentis quae anatomes studioso debent esse ad manum_. Let us now follow one Vesalius’s public courses in anatomy. It is the month of December, in the year 1537. The report has spread that the young Belgian professor will begin his course. Long before the hour set for the lecture, every available seat has been taken and many persons are standing. An audience comprising the professors of the University, the students of medicine, officials of the city of Padua, and learned persons of all ranks, including members of the clergy, numbering more than five hundred persons, has assembled to do honor to the professor of anatomy.