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."
The period immediately succeeding 1841, was, however, a time pregnant with new developments. The study of protoplasm soon engaged the attention of Von Mohl. Apical growth was investigated by Naegeli and Leitgeb. The discovery of the sexuality of ferns, and the completion of the life-story by Bischoff, Naegeli, and Suminski led up to the great generalisation of Hofmeister. And thus the years following 1841 witnessed the initiation of morphology in its modern development. On the other hand, Lyell's Principles of Geology had appeared and obtained wide acceptance. Darwin himself was freshly back from the Voyage of the "Beagle," while Sir Joseph Hooker, then a young medical man, was at that very time away with Ross on his Antarctic voyage, and shortly afterwards started on his great journey to the Himalaya. These three great figures, the fore-runner of Evolution, the author of the Origin of Species, and Darwin's first adherent among biologists, were thus in their various ways working towards that generalisation which was so soon to revolutionise the science of which Kew was to become the official British centre. Well may we then regard
