As the date of Sir William's appointment may be said to be the birth-day of the new development of Kew, it will be well to pause a moment and consider the position of botanical affairs in Europe at that time. The glamour of the Linnaean period had faded, and the Natural System of Classification of Plants initiated by De Jussieu had fully established its position, and had been worked into detail, taking its most elaborate form in the _Prodromus Systematis Naturalis_ of Augustin Pyrame De Candolle. That great luminary of Geneva died in this very year of 1841, leaving his work, initiated but far indeed from completion, in the hands of his son Alphonse. In England, Robert Brown was in the full plenitude of his powers, and in possession of the Banksian herbarium was evolving out of its rich materials new principles of classification, and fresh morphological comparisons. In fact morphology was at this time being differentiated from mere systematic as a separate discipline. Nothing contributed more effectively to this than the publication of _Die Botanik als inductive Wissenschaft_, by Schleiden, the first edition of which appeared in 1842: for in it development and embryology were for the first time indicated as the foundation of all insight into morphology. But notwithstanding the great advances of this period in tracing natural affinities, and in the pursuit of morphological comparison, branches which would seem to provide the true basis for some theory of Descent, the Dogma of Constancy of Species still reigned. It was to continue yet for 20 years, and the most active part of the life of the first Director of Kew was spent under its influence. Meanwhile great advances had been made also in the knowledge of the mature framework of cell-membrane in plants. Anatomy initiated in Great Britain in the publications of Hooke, Grew, and Malpighi, had developed in the hands of many "phytotomists," the series culminating in the work of Von Mohl. But it was chiefly the mere skeleton which was the subject of their interest. Eight years previously, it is true (1833), Robert Brown had described and figured the nucleus of the cell, and approached even the focal point of its interest, viz. in its relation to reproduction. But the demonstration of the cytoplasm in which it was embedded was yet to come. In fact, the knowledge of structure omitted as yet any details of that body which we now hold to be the "physical basis of life."