Contents: Introductory; The Founders of Natural Classification; The Pioneer Investigators in Photosynthesis; Robert Brown; Hofmeister on the Vascular Cryptogams; The Influence of the Origin of Species on Botanical Research; The Taxonomy of Cryptogams; The Ascent of Sap; Metabolism; Modern Views on the Composition of Chlorophyll; The Pteridosperms and the Seed; Conclusion; Bibliography; Explanation of Table; Index.