Such observations as these must not be understood in any sense of disparagement of the work of this great man. They are merely intended to indicate his historical position. The _Origin of Species_ was, it is true, published some few years before the _Synopsis Filicum_. But we must remember that Sir William Hooker was already an old man. Few men over 70 years of age alter their opinions, and the labourer who had grown old under the belief in the Constancy of Species could not in a few brief years be expected to change the methods of thought of a long and active life. We must take Sir William Hooker as perhaps the greatest and the last of the systematists who worked under the belief in the Constancy of Species. Because we have adopted a newer point of view, and take into consideration facts and arguments which were never his, and come to different conclusions now, is no reason for valuing one whit the less the achievements of this great botanist. His published work was just as much fundamental as was his official work. We have seen how he provided in Kew the means of indefinite development later, by constructing the coordinating machine with its collections and its libraries. In somewhat similar sense his publications were also fundamental. He did not himself construct. There is, I believe, no great modification of system or of view which is to be associated with his name. But in the wealth of trustworthy detail, recorded both pictorially and in verbal diagnoses, he has supplied the foundation for future workers to build upon, laid surely and firmly by accurate observation, and therefore durable for all time.