In the summer of 1740, he delivered a course of lectures on botany, and published a new edition of his Fundamenta Botanica, which he dedicated to Dillenius, Haller, Van Royen, Gronovius, Jussieu, Burmann, and Ammann; showing, in this classification, his opinion of the comparative merits of the most eminent botanists of that time. His medical practice continued to increase; and with his lectures, his private studies, and his duty as physician to the Admiralty, his time was fully and satisfactorily occupied. His former protector, Olaus Rudbeck the younger, professor of botany, having died in the spring of this year, Linnaeus, Rosen, and Wallerius offered themselves as candidates for the vacant office. Count Tessin supported the first mentioned; but the chancellor, Count Gyllenborg, gave Rosen the preference, as he had taken his degrees before the other, and had acquired stronger claims on the public by a longer residence at Upsal. The king, however, was desirous of bestowing the office on the great botanist, who was consoled for the loss by the promise of succeeding Roberg, who held the chair of medicine and anatomy. That gentleman, being advanced in years, requested permission to resign, which was granted; but although the appointment had been promised to Linnaeus, it was not without difficulty that he obtained it. In the mean time, Wallerius, his rival, took every opportunity of impugning his botanical doctrines, with the view of lessening the estimation of his merits; though the effort tended only to bring himself into contempt.