HOW PLANTS GROW 



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acteristics, whether it is found in the finger of man or in 

 the twig of a tree. 



The word " protoplasm " means first formed. Every part 

 of plants and animals was made from it. In reality, it is 

 the only part of an organism that can grow. Only a small 

 part of a tree is really alive, since only that small part 

 contains protoplasm. 



104. Cells. Protoplasm does not usually occur in large 

 masses, but in tiny lumps, each separated from the next 

 by a more or less distinct wall. 



It is these walls that give the 

 plant strength. Each separate 

 lump, with the wall about it, 

 is called a cell. If one had eyes 

 sharp enough to see all the cells 

 of a stalk of corn at one time, 

 the stalk would resemble a tall, 

 oddly shaped building, whose 

 outside walls would appeal- 

 composed of irregular masses 

 cemented together, not unlike 

 the stones in the wall of an 

 ordinary house. Within the stalk, long, hollow, cell-like 

 pipes could be noticed ; and around the pipes, separating 

 them from one another, countless round bodies (the pith 

 cells) might be observed. The cells of the cornstalk have 

 many different shapes, just like the parts of this imagi- 

 nary building. Some cells are as irregular as the corn- 

 stalk itself ; others have the shape of cubes, wedges, 

 plates, or strings. 



105. How Plants Grow. Floating in the protoplasm of 

 each live cell is a small rounded body known as the 

 nucleus. This nucleus is an important agent in the 

 growth of new cells. Cells, as we have said, never attain 



PLANT CELLS. 



As seen in a growing onion 

 root. 



