1. The sporophyte of Lemna minor cannot be definitely homologized with either a stem or a leaf, but is a shoot undifferentiated except at the basal and nodal regions. 2. The secondary root is formed from a group of hypodermal cells at the node. The epidermis, which is pushed out, persists for a considerable time as the temporary root-sheath. The root-cap while young adheres to the main body of the root, but later becomes entirely free except at the growing point. The number of cells constituting the meristem region is unusually small, sometimes being reduced to one or two. An axial strand of undifferentiated cells is the representative of the conducting system of the root. 3. Flowers are rarely formed, and when present part or all of their organs may disorganize at any stage in their development. 4. In young flowers the nucellus and stamen papilla first appear, and about the nucellus is the beginning of the carpel. The spathe appears outside of the carpel and stamen papilla. The two stamens arise from the...