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Show 294 DICECIOUS AND CHAP. VII. known to be dicecious. My son William found the two sexes growing in about equal numbers in the Isle of Wight, and sent me specimens, together with obser· vations on thein. Each sex consists of two sub-forms. The two forms of the Inale differ in their pistils: in some plants it is quite small~ without any distinct stigma; in others the pistil is Inuch moro developed, with the papillro on the stigmatic surfaces moderately large. The ovules in both kinds of males are in an aborted condition. On n1y mentioning this case to Professor Oaspary, he exa1nined several male plants in the botanic gardens at Konigsberg, where there were no females, and sent me the accompanying drawings. Fig. 13. Long-styled male. Short-styled male. RHAMNUS CATIIARTICUS. (From Caspary.) In the English plants the petals are not so greatly reduced as represented in this drawing. My son observed that those males which had their pistils moderate! y well developed bore slighl y larger flowers, and, what is very reinarkable, their pollen-grains exceeded by a little in diaineter those of the n1ales with greatly reduced pistils. This fact is opposed to the belief that the present species was once heterostyled; for in this cttse it might have been expected that the shorterstyled plants would have had larger pollen-grains. In the female plants the stan1ens are in an extremely rudimentary condition, much more so than CH.\P. VII. POL YGAl\10US PLANTS. 295 the pistils in the males. The pistil varies considerably in length in the female plants, so that they may be divided into two sub-forms according to the Long-styled female. Fig. 14. Short·stylcd female. RHAMNUS CATIIARTICUS. length of this organ. Both the petals and sepals are decided! y smaller in the females than in the males ; and the sepals do not turn down wards, as do those of the male flowers when mature. All the flowers on the same male or same female bush, though subject to some variability, belong to the same sub-form; and ~s my son never experienced any difficulty in decidIng ~nder which class a plant ought to be included, he believes that the two sub-forms of the same sex do not graduate into one another. I can form no sa~is.factory theory how the four forms of this plant originated. Rhamnus lanceolatus exists in the United States as I am informed by Professor Asa Gray, under two' hermaphrodite forms. In the one, which may be called the short-styled, the flowers are sub-solitary, and includ~ a pistil about two-thirds or only half as long as that In the other form ; it has also shorter stigmas. The stamens are of equal length in the two forms; but the anthers of the short-styled contain rather less pollen, as far as I could judge from a few dried flowers. My |