We return, after this excursion into the curious world of the Algæ, to the higher plants, and inquire whether there are not special adaptations to a life in the water in the conditions of their blossoming.
The flower of the phanerogam is adapted in general to life in the air and the light. We find, therefore, that the flowers of many water plants with floating leaves aim to reach the surface of the water. They require for the transfer of the pollen to the ovule the aid of the wind or of the insects which hover thickly over the water. Their emergence is effected with the help of floats of various kinds, of which it is sufficient to recall here a much-cited example. In the Vallisneria, the long, grasslike leaves of which form a kind of turf at the bottoms of some of the south European lakes, the inconspicuous male flowers rise in knobby bunches protected by a turgid envelope at the bottom of the water. The female flowers stand singly on very long, threadlike stems which rise to the top of the water. When the pollen has matured, the covering of the male flowers opens and the flowers escape in the form of little balls, which, being very light, rise at once to the surface of the water. Here are unfolded three white leaves, which, to use a figure of Kerner's, float around like pollen-laden canoes, and are so wafted by the wind as to convey their freight to the female flowers. While the fruit is forming, the stems of the female flowers roll up spirally and draw the seeds down into the protecting deeps, to remain there undisturbed till the time of germination. The flowers of many water plants, except for these processes, remain concealed in the deep throughout their lives. They do not there bring all their functions to fruiting, which can be accomplished only in the air. Without color or fragrance, they are inconspicuous; their structure is distinguishable only under close examination, and they are proved to be real flowers only by their pollen-shedding and their formation of seeds. Again arise in water plants special tasks. It is incumbent upon one to spread itself as widely as possible and establish its posterity in new places, where it may obtain room for free development and will not be dwarfed under the shadow of larger plants. The seeds, therefore, must not stay where they have fallen when ripened. They must be scattered, and by all means carried away from the immediate neighborhood of the mother plant. The fruits or seeds of water plants are therefore largely endowed with aids to swimming, by the help of which they can accomplish long distances. They share this provision with many shore plants, the whole existence of which is connected with the water in more than one respect. Among these is the cocoa palm, the gigantic fruits of which are comparatively very light. Filled within with cocoanut milk and cocoa butter, food for the young sprout, they pos-
