. A manual of structural botany; an introductory textbook for students of science and pharmacy. Plant morphology. 96 POLLINATION AND FERTILIZATION 274. where self-pollination would otherwise commonly result, and it may be assumed to have been the first step toward the uni-sexual state, so common among flowers of that class. Careful notice should be taken of the fact that in dichogamj' the retarded state observed in androecium or gynaecium is but temporary, and that the finally developed form is the same, whether the flower be proterandrous or proterogynous. Dimorphism.—A far more profound modi
. A manual of structural botany; an introductory textbook for students of science and pharmacy. Plant morphology. 96 POLLINATION AND FERTILIZATION 274. where self-pollination would otherwise commonly result, and it may be assumed to have been the first step toward the uni-sexual state, so common among flowers of that class. Careful notice should be taken of the fact that in dichogamj' the retarded state observed in androecium or gynaecium is but temporary, and that the finally developed form is the same, whether the flower be proterandrous or proterogynous. Dimorphism.—A far more profound modification is that in which there is a permanent change in the androecium (Fig. 273) of one flower and a similar change in the gynaecium (Fig. 274) of another, by which a similar result is obtained to that proceeding from dichogamy. Such a provision constitutes Dimorphism. By a modification of it, a third form of flower, intermediate between the other two, is produced, con- stituting Trimorphism. The explanation of the case of dimorphism here exhibited is as follows: An insect visiting flower No. 1 and thrusting his proboscis deeply into the corolla- tube in search of nectar, brings his body into contact with the stamens, and pollen is deposited upon it. The next flower visited may be one like No. 2, having a long style. The por- tion of the body which is now covered with pollen will then be brought into contact with the stigma, upon which the pollen is deposited. At the same time a different part of the body is being laden with pollen from the short stamens of flower No. 2, to be deposited upon the short pistil of still another flower, similar to No. 1. If perchance two flowers of the same form are visited in succession, the result is that an additional deposit of pollen is secured, or at most a portion of the pollen already being carried is left upon the stamens of the visited flower. As will be seen by a consideration of typical examples of each, dimor- phism is more intimat
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