The Golden Rule for Flowers 191 



whose tall, handsome spikes of blossom light up the river 

 banks. The pistils and stamens of this plant are of three 

 different sizes, but they correspond exactly in height, long 

 pistils with long stamens, short with short, and middle- 

 sized with middle-sized. The long stamens have emerald- 

 green pollen, the others yellow; and the grains vary in 

 size with the length of the stamens, the longer the stamens 

 the larger the grains; for the larger grains are destined 

 for the longer pistils, and have, of course, to send out 

 longer tubes in order to reach the ovules. 



A bee entering a blossom in search of honey is dusted 

 with pollen on different parts of its body, according to 

 the height of the stamens, and when it flies off to the 

 blossoms of another plant, if the spots of dust come in 

 contact with pistil-tips of the proper height, they may be 

 caught and kept. 



The red Oxalis is another of the plants having pistils 

 and stamens of three sizes, and a large field in Brazil con- 

 taining many acres of this plant yielded not a single seed, 

 because, though pollen and insects were both plentiful, all 

 the plants chanced to be of the same "form," as it is 

 called — all had long pistils and short stamens, or vice 

 ve7'sd, and the pollen was of no use. Other plants pos- 

 sess similar pecuharities, but we will mention one which 

 all can examine for themselves, the common yellow prim- 

 rose. 



The blossom of the primrose is a long tube flattened 

 out at the top into five divisions. If we look at a bunch 

 of primroses gathered from different plants, we see at 

 once that all are not alike. In some the pistil, with a 

 knob like a pin's head, stands up just out of the tube; in 

 others no pistil is visible, but in its place, just at the same 



