52 



DOMESTIC BOTANY. 



barberry, Kalmia, and Stylidium; or by forcible discharge 

 from the anther, as readily seen in pellitory and nettle, 

 the pollen looking like puffs of smoke, giving the idea 

 of a miniature cannonade. 



Flowers have been compared to public-house signs, 

 inviting guests to a repast, the guests being the insects, 

 and the viands pollen and honey. By the movement of 

 the insect in the flower the pollen becomes dislodged 

 from the anther and dispersed ; some of it comes in 

 contact with the stigma, or by adhering to the insect, is 

 carried by it to other flowers. In some cases it is 

 necessary for the insect to be caught in the flower, which 

 in Aristolochia is accomplished by the inside of the tube 

 being beset with stiff hairs pointing downwards, like a 

 mousetrap. This is more remarkable in the pretty 

 orchid genus Pterostylis, the flower being in the form of 

 a hood or cowl, open in front, from which hangs the part 

 called the lahellum, in the form of a strap or tongue ; 

 on this being touched by an insect entering, it imme- 

 diately turns up like a flap and imprisons the intruder. 

 In some of the Pea and Trumpet flower families. Snap- 

 dragon, Monkey flower, and others, bees find it diffi- 

 cult to enter, but have sufficient instinct to know that 

 the honey lies at the bottom of the flower, and in order 

 to obtain it they cut a hole in the side, thus leaving the 

 pollen untouched. The viands, however, are not always 

 pollen and honey ; in the remarkable flowers of Rafflesia, 

 Stapelia, and Aristolochia, the bluebottle and other flies 

 are attracted by their carrion-like odour, and even deposit 

 their eggs in them. In many flowers, such as orchids 

 and asclepiads, insects are indispensable for bringing the 

 pollen in contact with the stigma. 



After having received the pollen, the stigma is said 



