Movements of Plants. 307 



pjass, and promoting the thorough mixture of its different por- 

 tions so as to render it perfectly homogeneous in every region 

 f the globe, and at every elevation above its surface. 



Thus are the two great organized kingdoms of the creation 

 pade to co-operate in the execution of the same design ; each 

 ministering to the other, and preserving that due balance in the 

 constitution of the atmosphere, which adapts ir 1o the welfare 

 a nd activity of every order of beings, and which would soon be 

 destroyed, were the operations of either of them to be sus- 

 pended. It is impossible to contemplate so special an adjust- 

 ment of opposite effects, without admiring this beautiful dis- 

 pensation of Providence, extending over so vast a scale of 

 being, and demonstrating the unity of plan on which the whole 

 system of organized creation has been devised. 



MOVEMENTS OF PLANTS. 



Some of the most interesting among the vegetable move- 

 ments are concerned in the deposition of the seed. The Bal- 

 sam, (Impatiens) has a capsule formed of two valves, which, 

 when the seed is ripe, suddenly separate from one another and 

 curl inwards, scattering the seed to some distance. Now an 

 examination of the tissue of these valves shows that their outer 

 part consists of cells much larger than the inner, and that the 

 fluid contained in it is the most dense. By the laws of Endos- 

 mose, (page 121,) therefore, the fluids contained in the tissue 

 of the interior, will have a tendency to pass towards the out- 

 side, and will still more distend the cells of that part. This 

 distention of the outside layer will manifestly give the valves 

 a tendency to curl inwards ; just as "when two thin plates of 

 metal, which expand unequally by heat, are soldered together, 

 and, heat being applied, the compound plate bends towards 

 the side which expands least. -This tendency continues to in- 

 crease up to the time when the seed is ripe ; and it is then so 

 powerful as to cause the separation of the valves from each 

 other, and to occasion the rolling inwards of each. Now it has 



