The year before the publication of the _Prodromus_, Brown communicated to the Linnean Society an excellent and learned memoir on the Proteaceae. In this paper we encounter an instance of that whimsical introduction of observations exceedingly valuable in themselves, but mainly irrelevant to the matter in hand, which is a characteristic feature of many of his works. Perhaps it was due to the intense keenness with which he always followed up problems that interested him, so that, like Mr Dick's weakness for King Charles' head, they had to find a place in whatever else he was writing about. Thus his treatise on the Proteaceae starts off with advice to study the flower in the young, instead of only in its adult condition, and this is driven home by an excellent disquisition on the structure of the androecium and gynaeceum of Asclepiads, a subject which occupied his mind for some years and formed the basis for separate papers at subsequent periods. Only when he has discussed the morphology of the Asclepiad flower does he plunge, abruptly, into the questions relating directly to the Proteaceae. Later on in the same year (1809) he read a masterly paper on the Asclepiadaceae which was subsequently printed in the _Memoirs_ of the Wernerian Natural History Society. This Natural Order was here separated by him from the Apocynaceae, from which it had not previously been distinguished, and a correct account of the relations of the remarkable androecium, so characteristic of the Asclepiad flower, was given. Twenty-two years later (in 1831) he again returned to the Asclepiads and described and discussed the mode of pollination and fertilisation in this Order and also in that of the Orchids. It was characteristic of Brown that he clung with great tenacity to any problem that had once excited his interest. He made himself fully acquainted with the work of his contemporaries and predecessors, and at the same time he constantly attacked it by reiterated first-hand investigations, testing hypotheses and theories by the light of direct observation. He was very cautious, and thus, although he traced the pollen tubes from the pollen grain into the ovary and into the micropyle (foramen) of the ovule, he still leaves it an open question whether, in all cases, anything of a material nature passes from the pollen to the interior of the ovule, which may thus be held responsible for the formation of an embryo.