THE GLAUCOUS BIRTHWORT. 79 



anthers closed over the pointal, and the prey cap- 

 tured. 



The different manner in which vegetables exert 

 their organic powers to effect the destruction of 

 insects is not, perhaps, unworthy of a brief notice ; 

 some, as those above mentioned, accomplish it by 

 means of elastic or irritable actions, adhesive 

 substances, and so forth; but we have another 

 plant in our greenhouses, the glaucous birthwort 

 (aristoL glauca), that effects these purposes with- 

 out any of these means, but principally by con- 

 formation. The whole internal surface of the tu- 

 bular flower is beset with minute strong spines, 

 pointing downwards ; these present no impediment 

 to the descent of the animal which may seek for 

 the sweet liquor lodged upon the nectarium at the 

 base of the blossom, nor is there any obstruction 

 provided for its return by means of valves or con- 

 tractions, the tube remaining open ; but the crea- 

 ture cannot crawl up by reason of the inverted 

 spines ; and to prevent its escape by flying up the 

 tube, the flower makes an extraordinary curve, 

 bending up like a horn, so that any winged crea- 

 ture must be beaten back by striking against the 

 roof of this neck as often as it attempts to mount, 

 and falling back to the bulbous prison at the base 

 of the blower, dies by confinement and starvation, 

 and there, we find them : a certain number of these 

 perishing, the blossom fades and drops off. 



The fluids secreted by the nectaries of plants, 

 being commonly sweet, are much sought after by 



