SCIENTIFIC RECREATIONS. 



receive the pollen-grains. In many plants, however, the stamens are too- 

 short to reach the pistils ; or the two essential organs of reproduction are in 

 separate flowers, or even on different plants. In such cases, the conveyance 

 of the pollen from the anthers to the pistils is effected by the agency of the 

 wind, or by that of insects, and more particularly by the bee. If the anthers 

 are removed from the flower previously to their opening, no fruit is produced.. 

 Varieties of flowers and fruits are produced artificially, by shaking the 

 ppllen of one plant upon the flowers of another, deprived of the stamens. 

 Many esteemed sorts of stock-gilliflowers and pinks have been produced in 

 this way. 



The pistil constitutes the fourth and innermost whorl, and occupies 

 accordingly the centre of the flower and the apex of the axis, whose growth 

 is terminated with the production of the fruit. 



The pistil also is formed by one or several modified leaves, called 

 carpels, in this part of the flower, and which exhibit 

 a more marked resemblance in colour and struc- 

 ture to the ordinary leaves than the stamens and 

 petals do. The formation of the pistil from the leaf 

 may be considered to proceed in this manner : that 

 the edges of the leaf are folded inwards and unite, 

 whilst the mid-rib is prolonged upwards (fig. 7?6A). 

 The place where the margins of the folded leaves 

 are united is called suture or seam (ventral suture ', 

 in contradistinction to the mid-rib, which is called 

 the dorsal suture) ; and it is here that the seed-buds or ovules are developed. 

 The pistil consists of two parts viz., the ovary or germen, which con- 

 tains the ovules or young seeds, a, and the stigma, b, either placed upon the 

 ovary, or upon the style, or stalk, which is between the stigma and the ovary. 

 A pistil may be of one carpel (simple), or of more than one (compound). 

 The carpels or the carpellary leaves are the "ovaries." 



The pistil is a very important test for the classification of plants; some 

 trees have no pistils, and the ovules are consequently naked. Such plants 

 are called gymnospcrmce. The coniferae (firs and pines) are thus recognizable, 

 and the position of the ovule is very much that of the ordinary bud. 



Fig. 776. Pistil. 



