PART I. 



VEGETABLE PHYSIOLOGY. 



1. Botany is that science, wliicli treats of plants, and in 

 its most extensive application makes us acquainted with the 

 structure, vital action, classification, uses and distribution of 

 vegetables. 



2. A plant is an organized being, receiving its nourish- 

 ment, which is always Huid, by absorption, generally through 

 roots, and elaborating it by exposure to the combined action 

 of air and light, on the surface of leaves or stem, and after- 

 wards assimilatinji it to its own substar^e. 



To the common observer it is not difficult to make a dis- 

 tinction, between a plant and an animal on the one hand, or 

 a plant and a mineral on the other. But however unlike the 

 three great kingdoms of nature. Animal, Vegetable and Min- 

 eral, may be, in their common forms, yet they approach each 

 other by almost insensible gradations, and in certain objects 

 it is difficult, for even the most accurate observer, to draw 

 unerringly the line of demarcation. We see the Porifcra* 

 covering the rocks of tlie ocean, hanging in living festoons 

 from the arches of caves, and clothing the otherwise naked 

 clitfs, exposed to the alternate action of winds and waves, and 

 firmly fixed to their several locations, and at the same time, 

 perhaps, observe the floating Algie, apparently destitute of 

 roots, absorbing its nourishment through its whole surface, 

 and in some degree endowed with the power of locomotion. 

 In what respect does our definition exclude the porifera from 

 the vofTctablc kinffdom and embrace the Aljja3 in it ? The 

 manner in those cases in which the food is elaborated decides 

 to which kingdom the individual belongs. The immoveable, 

 and vegetable-like Porifera, has an internal organization, 



♦ sponges. 



