250 



THYTONOMr. 



When we see the antherae, which previously were included 

 within the concave parts of the corolla or calyx, suddenly and 

 powerfully raise themselves up and scatter their pollen, we 

 can only attribute this to the relaxation of the contraction of 

 the parts. When we see fruits or capsules spring up with 

 yet greater elasticity, or scatter their seeds, we find upon ex- 

 amination that this also is a consequence of the preceding 

 contraction, which in the Acantheae, for example, is occasion- 

 ed by peculiar hooks on the dissepimentum ; (Tab. I. Fig. 

 37.) 



To the same class we refer other phenomena, which, in our 

 opinion, are falsely considered as effects of higher powers. 

 The springing back of the sexual parts of the Medicago spe- 

 cies on the vexillum, by the contact of the carina, is as cer- 

 tainly a consequence of the excited elasticity of the parts, as 

 the elevation of the fruit-stalk of the Stylidiae, which was pre- 

 viously pressed into double curvature, and was held in a state 

 of contraction by a peculiar pointed petal, until, after the 

 complete evolution of the blossom, this petal relaxes, and thus 

 leaves the fruit-stalk at liberty, which then stretches and 

 raises itself up, although it still continues curved ; (Fred. 

 Bauer, lUustr. Nov. HoU.) The irritability of the arched 

 margin of the corolla of the Leeuwenhoekia, R. B. is to be ex- 

 plained in the same manner. An irritability has also been 

 ascribed to the parts of the glume oi the Leersia lenticularis^ 

 Mich., which is known in North America under the name 

 of the Fly-catching Grass ; but it has been lately shewn, 

 that the notched cilia of the valves detain the proboscis of 

 flies, when they stick in them, in a manner entirely mechani- 

 cal ; (Nuttall, Genera of North American Plants.) In our 

 Drosera also, as in the Roridula of the Cape, the catching 

 of flies seems to be merely a consequence of the sticking of 

 the insects to the glands of the leaves. 



We cannot determine with certainty whether the opening 

 and shutting of the lid of the water-bladder in the Nepen- 

 thes distillatoria, CcpJialotus Jblliadaris, and of the hollow 

 leaves in the Sarracenice, is merely the consequence of a me- 

 chanical arrangement. In the Ccphahtuis at least, there h a 



