FAJIILIAR LESSOKS IN BOTAXY, 



are produced by the deposit of sclerogen, and this is the 

 substance that forms the peach-stone, cherry-seed, etc. 

 Professor Lindley demonstrated concerning celhilar tissue 

 that it has the power of reproducing itself. He estimated 

 the production of mushroom cells to be at the rate of four 

 billions per hour. 



182. These cells are not always the same shape or size. 

 Sometimes they are like honeycomb. You find leaves, 

 pith, and most kinds of fruits presenting this form of celL 

 Again they are arranged in parallelogram form, like bricks 

 in a wall, and are therefore called muriform; they are also 

 egg-shaped, and sometimes round, looking like a pile of 

 balls. 



183. Among those cells other little organs or cells are 

 sometimes found. They are called receptacles of secretion. 

 Here are found oil, as in olive, myrtle, and orange ; turpen- 

 tine, as in the pine and fir; coloring matter, as in woad, 

 logwood, and madder. 



184. You were told just now that these cells looked 

 sometimes like balls piled one upon another, as you see 

 cannon-balls in forts and arsenals. In these the interstices, 

 or openings between, can be easily enough seen. These cells, 

 whatever their shape, have cavities, which are called inter- 

 cellular passages, and are filled with fiuids. They com- 

 municate with the open air through the pores that you have 

 been told cover the epidermis. 



185. Cellular tissue decays early, as you will perceive in 

 fruits and the lamina of th-e leaves ; while the seed of the 

 fruit and the veins of the leaves, being formed of a firmer 



182. Are these cells always shaped alike? Where do you find them shaped 

 like honeycomb cells ? 



183. What is found among these cells ? What are they called ? What is found 

 here? 



184. Are there cavities in the cells ? What are they filled with ? How do they 

 communicate with the outer air ? 



185. Does cellular tissue decay early ? What of woody tissue ? What of the 

 bundles of tubes ? With what were they a long time confounded ? What has tho 

 microscope demonstrated ? What are they ? 



