142 VEGETABLE FABRIC. [LESSON 23. 



of the cells in number. It is by the latter, of course, that the prin- 

 cipal increase of plants in bulk takes place. 



LESSON XXIII. 



VEGETABLE FABRIC t CELLULAR TISSUE. 



391. Organic Structure! A mineral such as a crystal of spar, or 

 a piece of marble may be divided into smaller and still smaller 

 pieces, and yet the minutest portion that can be seen with the mi- 

 croscope will have all the characters of the larger body, and be 

 capable of still further subdivision, if we had the means of doing it, 

 into just such particles, only of smaller size. A plant may also be 

 di\i(lcd into a number of similar parts: first into branches; then 

 each branch or stem, into joints or similar parts (34), each with its 

 1 af or pair of leaves. But if we divide these into pieces, the pieces 

 an: not all alike, nor have they separately the . properties of the 

 \\ hole ; they are not whole things, but fragments or slices. 



.'. If now, under the microscope, we subdivide a leaf, or a piece 



of >tMi\ or root, we come down in the same way to the set of similar 



tiling it H made of, to cavities with closed walls, to Cells, as \ve 



call them (.'5*0), essentially the same everywhere, however they may 



in -hape. These are the units, or the elements of which every 



"HH>ts ; and it is their growth and their multiplication which 



540. MaKniflod Y'CW, or diagram, of some perfecth rpfrular cellular tissue, formed of 



i iiinl li-i^thwi-.,-. 



