It was supposed that botany had reached its culminating point in Linnaeus and that improvement could only be made in details--elaborating and extending his system. As Sachs tells us in his _History_, the result was that "Botany ceased to be a science; even the describing of plants which Linnaeus had raised to an art became once more loose and negligent in the hands of his successors. Botany gradually degenerated under the influence of his authority into an insipid dilettantism--a dull occupation for plant collectors who called themselves systematists, in entire contravention of the meaning of the word." This was written with especial reference to Germany, but it applied with no less force to our own country where the Linnaean idea had taken deep root and the Linnaean collections had found a sanctuary. However, by 1840, a change was coming over the face of botany. Little as it can have been dreamt, the Golden Age was already beginning--destined in a relatively short time to transform the subject. This Golden Age was contemporaneous with, and immediately dependent on, the rise of a group of young botanists in the Fatherland, a group which included von Mohl, Schleiden, Hofmeister, Nägeli, Cohn and De Bary. Later it was reinforced by Sachs, who in addition to being a brilliant physiologist was a gifted writer who did much to establish scientific botany on a sound footing. It is impossible to overestimate the debt due to Sachs, particularly for his great _Textbook of Botany_, which at the right psychological moment brought the whole of the modern work between the covers of a single volume. It was with the dawn of this period that Henfrey identified himself. In the 15 years of his active career (1844-1859) he devoted himself very largely to making his fellow-countrymen acquainted with the newer aspects of botany. More particularly it was the recent discoveries as to the reproduction and life history of the Vascular Cryptogams that specially engaged his interest--the researches which broadly speaking we associate with Hofmeister to-day. Before we go on to speak of the sexuality of the Cryptogams however, a few words may be devoted to that of the flowering plants. _Sexuality of Flowering Plants._ At the period when Henfrey entered on his career as a botanist no reasonable doubt remained as to the existence of sexes among the flowering plants. The theory of the sexual significance of the organs of the flower, brilliantly founded by Koelreuter in the previous century, had been perfected with a great volume of experimental proof by K. F. Gaertner the son of Joseph Gaertner of _Carpologia_ fame.