i8 EXAMINATION OF [CHAP. 



carpels to mature into fruit. But they do not generally 

 fall until after an important function has been accom- 

 plished by the stamens, either of the same flower, or of 

 another flower of the same kind of buttercup. This 

 function we shall briefly refer to here, deferring a fuller 

 account of it to a later chapter, when we shall have to 

 compare the stamens and carpels of the buttercup with 

 the stamens and carpels of other plants. 



The two outer series of flower-leaves, the sepals and 

 petals, may be regarded simply as organs designed to 

 protect the smaller and delicate parts which they enclose 

 during their early development; and perhaps, also, from 

 their more showy colour and greater size they may serve 

 to attract insects which, we shall find, have an important 

 work to perform, as aids in securing the formation of 

 good seed. Hence the calyx and corolla are termed the 

 envelopes of the flower. As both calyx and corolla are 

 present in the buttercup, the envelope of the flower is 

 double, or in two series. Hence the flower is termed 

 dichlamy 'deous. 



3. The anthers, we have observed, are divided length- 

 wise into two lobes, which lobes, after the expansion of 

 the flower, become fissured near their margins, so as to 

 liberate the grains of pollen which they contain. About 

 the time that the anthers open to discharge their pollen, 

 we may observe the stigma of each of the carpels to be 

 rough with minute projecting cells, which, on careful 

 microscopic examination, we shall find to be slightly 

 moistened. Upon the stigmas, after the flower has been 

 open a few hours in fine weather, there may usually be 

 found a few grains of pollen, which have either reached 

 the stigma by direct contact of the anthers, or by means 

 of some insect visiting the flower in search of nectar, and 

 which, unwittingly, conveyed some of the pollen, acci- 

 dentally adhering to its hairy limbs and body, to the 

 stigma. This transfer of the pollen from the anthers to 

 the stigma is of essential importance. If we separate a 

 few stamens, with their anthers and pollen, and keep 

 them apart from the rest of the flower ; or if we remove 

 all the carpels in a bud, so that stamens only remain 

 within the envelopes, we shall find that they ultimately 

 shrivel and wither up pollen- grains, and all without 



