The first chapter gives an account of the principal writers on botany; the second, of systems of classification; the third, of the roots, stems, and leaves of plants; the fourth, of the parts of fructification. In the remaining chapters are discussed the doctrine of sexes, the characters of the classes and subdivisions, the names of the genera, the specific differences, varieties, synonymes, the descriptions of the species, and the virtues or uses. At the end of the volume are several curious fragments, containing directions to students of botany, the method of forming herbariums, a plan to be followed by naturalists in travelling, and other matters of a like nature. "The Genera Plantarum," says Linnaeus in his private memoirs, "the most important of all the works on botany, and which was intended for facilitating the study of that science, being completed, he laboured at the species. He was at this period the only person who had at his disposal the materials necessary for the composition of that great work. His herbarium was immense, and no one had seen so great a number of gardens and collections. With the assistance of this methodical book, any person can make out the plants already described by authors, and those which have become known only of late, or which are entirely new. He laboured, two successive years at the species; and it was at this period that he felt the first attacks of calculus, the usual consequence of too sedentary a life, and of long-continued pressure on the lower abdominal viscera." In 1753, being again called to Drottningholm, he was desired to describe the natural productions contained in the museums of his majesty and the Count Tessin. The former rewarded him with a valuable ring, the latter with a gold watch and a copy of Rumphius's splendid Herbarium Amboinense. But what delighted him most was the assurance given by the queen, that should his son evince a liking to natural history, she would send him to travel over Europe at her own expense.