The pistil consists of three parts, viz. a swollen base, the _ovary_ (fig. 41 _b_), surmounted by a column or _style_ (fig. 41 _a_), and which is crowned by a viscid and often hairy summit, the _stigma_ (fig. 40*). In chickweed there are 3 styles. It must be remarked that, in the flowers of some plants, stamens alone are present, while others contain pistils only, although most flowers contain both organs. When the stamens and pistils occur in separate flowers on the same plant, the plant is said to be _monœcious_ (μὁνος, single, οἶκος, family); when all the flowers of distinct plants contain either stamens only or pistils only, the plant is _diœcious_ (δις, twice, οἶκος); and when the stamens and pistils occur together in all the flowers of the same plant, the plant is said to be _hermaphrodite_. These terms had their origin in the idea that the differences of plants in respect to these organs were analogous to those of the sexes in animals. All the parts of a flower have their special uses: thus the calyx and corolla protect the delicate organs enclosed by them, until they attain maturity. The petals also, by their brilliant colours, attract insects which feed upon or collect the honey of the flowers; these at the same time conveying the pollen which adheres to their bodies from one flower to the stigma of another. The stamens and pistils are organs of fructification, it being essential for the fertilization of the flowers that the pollen should come into contact with the stigma. We will now consider some interesting points of structure in these organs.