CHAPTER I. 

 THE STRUCTURE, FORM AND DEVLLOPMENT OP THE OPASSES. 



Protoplasm is the living portion of a plant. It is sensitive 

 to heat and cold and is the essential part without which the 

 cell cannot live, take in or assimilate food or make any growth. 

 Protoplasm is a soft-solid, generally containing a multitude of 

 small granules, and when everything is favorable it is in unceas- 

 ing motion. Delicate currents, often changing in direction and 

 rapidity, are traced by the granules which they carry as they 

 gracefully glide from one part of the cell to the other. Under 

 the microscope this motion may be seen in the sting of a nettle, 

 hair of a pumpkin vine, style of Indian corn, or a hair at the tip 

 of a young kernel of wheat and in many other parts of plants. 

 Protoplasm is most abundant in the newer or younger portions of 

 the roots, stems, leaves, buds and seeds, and constitutes most of 

 the nourishment as food for herbiverous animals. Very young 

 cells are filled with protoplasm, while the older ones contain less, 

 little, or none. 



Cells. All parts of plants, except a few very small one-celled 

 species, are composed of cells which are generally microscopic. 

 When any part of a plant is soft and can be easily crushed or 

 broken in any direction, the cell walls are thin; when it is hard 

 the cell walls are thick ; when tough like the fibre of flax, the 

 cell walls are quite long and have thick walls. 



Chlorophyll. All the green parts of a plant are so colored by 

 a little green substance called r/^/oro^^/^y/, without which the 

 plant is unable to assimilate any thing or to make any real prog- 

 ress in growth. 



