Schleiden was acquainted with Schwann, and in October, 1838, while the two were dining together, he told Schwann about his observations and theories. He mentioned in particular the nucleus and its relationship to the other parts of the cell. Schwann was immediately struck with the similarity between the observations of Schleiden and certain of his own upon _animal_ tissues. Together they went to his laboratory and examined the sections of the dorsal cord, the particular structure upon which Schwann had been working. Schleiden at once recognized the nuclei in this structure as being similar to those which he had observed in plants, and thus aided Schwann to come to the conclusion that the elements in animal tissues were practically identical with those in plant tissues. Schwann.--The personalities of the co-founders of the cell-theory are interesting. Schwann was a man of gentle, pacific disposition, who avoided all controversies aroused by his many scientific discoveries. In his portrait (Fig. 74) we see a man whose striking qualities are good-will and benignity. His friend Henle gives this description of him: "He was a man of stature below the medium, with a beardless face, an almost infantile and always smiling expression, smooth, dark-brown hair, wearing a fur-trimmed dressing-gown, living in a poorly lighted room on the second floor of a restaurant which was not even of the second class. He would pass whole days there without going out, with a few rare books around him, and numerous glass vessels, retorts, vials, and tubes, simple apparatus which he made himself. Or I go in imagination to the dark and fusty halls of the Anatomical Institute where we used to work till nightfall by the side of our excellent chief, Johann Müller. We took our dinner in the evening, after the English fashion, so that we might enjoy more of the advantages of daylight." Schwann drew part of his stimulus from his great master, Johannes Müller. He was associated with him as a student, first in the University of Würzburg, where Müller, with rare discernment for recognizing genius, selected Schwann for especial favors and for close personal friendship. The influence of his long association with Müller, the greatest of all trainers of anatomists and physiologists of the nineteenth century, must have been very uplifting. A few years later, Schwann found himself at the University of Berlin, where Müller had been called, and he became an assistant in the master's laboratory. There he gained the powerful stimulus of constant association with a great personality. [Illustration: Fig. 74.--Theodor Schwann, 1810-1882.]