In this paper the author alluded to the spore as the ultimate germinating cell of cryptogamic plants. The true spore is the product of impregnation, but there are also bodies called spores which, so far as known, do not depend on the process of fertilisation. Occasionally the term spore includes both the spore and the spore-case or sporangium. The structure of the spore was described, and its resemblance to the pollen grain, both as regards its anatomy and germination, was shown. Ciliated moving spores were considered, and reference was specially made to the movements of the non-ciliated spores of Helminthora, which, when discharged, continue to change their form for several hours like the Amœba, becoming in turn oblong, pyriform, rhomboidal, &c.,—lengthening and contracting, swelling at one point and shrinking at another.