"The special researches of the Bonn epoch are those of the minute structure and anatomy of the glands. They put an end to the controversy which had existed so long between adherents of Malpighi and Ruysch, concerning the sacculated extremities of the glandular follicles, and obtained for us a correct knowledge of these important organs throughout the whole animal kingdom. Perhaps his most important work is that of the Ducts of Müller, the structures (named after him) which form so important a part of the genito-urinary system in the embryo." Practically all this had been accomplished before he was {234} quite thirty-two years of age. In the autumn of 1832, Rudolphi, the professor of physiology at Berlin, died. As Virchow says, candidates sprung up on every side, and some who were the least qualified considered themselves best fitted for the position. Müller took an unusual step which illustrated his decision in character, though in any other it would have seemed an evidence of conceit. He declared, in an open letter, laid before the Minister of Prussia, that his claims were superior to those of any other living physiologist, except John Frederick Meckel. So powerful was the impression produced upon the minister by this letter that he immediately appointed Müller to the vacant chair. Not long after his appointment to the chair of physiology at the University of Berlin Müller completed the well-known "Hand-book of Physiology," which established his reputation. The book is sometimes spoken of as an experimental physiology, but this is not correct. Müller was no more a mere experimentalist than Haller, and he, himself, heartily detested the tendency which experimental physiology had assumed in France, especially under the influence of Magendie. Part of Müller's aversion to experimental physiology was aesthetic. He could not bear the idea of inflicting so much pain as many of his colleagues inflicted without a thought. In his panegyric of Rudolphi, Müller says: "Rudolphi looked upon physiological experiments as having no relation to anatomical accuracy, and it is no wonder that this admirable man, who had at every opportunity expressed his abhorrence of vivisection, took up a hostile position against all hypotheses and conclusions insufficiently established upon physiological experiments." Müller adds: "We could not have failed to share his righteous indignation, had we seen how many physiologists were using every effort to reduce physiology to an experimental science by the live dissection and agonies {235} of innumerable animals, undertaken without any definite plan, and yielding often only insignificant and imperfect results."