308 BEES AND BEE-KEEPING. 



and vetches, but in the scarlet runner a singular and 

 interesting modification must be noticed. The keel 

 is prolonged into a narrow snout, which is literally 

 coiled like a snail's shell, and through which the style, 

 similarly twisted, is prolonged. When a bee visits, 

 the stigma first makes its appearance, and then the 

 pollen-coated style, acting in the manner previously 

 noticed. The French bean has a structure identical 

 with that of the scarlet runner, and both yield honey; 

 yet the latter is sterile without insect action, while 

 the former, where no insect can fertilise it, may be 

 forced, yielding seed in full abundance by self- 

 impregnation. In the melilots and trifoliums, and 

 Onobrychis (sainfoin), we have the plants which most 

 gladden the bee-keeper's heart. Their honey is of 

 rare quality, and its amount is astonishing. Their 

 fertilisation is accomplished as before, with slight 

 differences, since the style is not brush-like, but the 

 anthers themselves pass out of the keel to give up 

 their pollen. Darwin points out the utility of bees 

 to these plants. The flowers of Trifolium incarnatum 

 (crimson trefoil), which were visited by bees, pro- 

 duced between five and six times as many seeds as 

 those that were protected (covered with a net). Of 

 Trifolium pratense (common purple clover), ioo 

 flower-heads on plants protected did not produce a 

 single seed, whilst ioo heads, on plants growing out- 

 side, which were visited by bees, yielded 2,720 seeds. 

 In Trifolium repens (white Dutch clover), the crossed 

 and self-fertilised plants yielded seeds in the ratio of 

 ten to one; and, in another experiment, twenty heads, 

 unprotected, yielded 2,290 seeds, while twenty pro- 



