THE TISSUES OF PLANTS. 21 



parts of plants, they are of greatest importance in the 

 present study. 



Practical Studies. — (a) Make very thin longitudinal sections of a 

 root of Indian corn. The large strong roots which first start out 

 from the germinating grain, and the youngest states of those which 

 appear just above the ground, upon the large plants, are best for 

 these specimens. Stain some of the sections with carmine. 



(b) Make very thin longitudiual sections of the opening buds of 

 the lilac or elder. 



(c) Malie similar sections of the tips of the young shoots of aspara- 

 gus. Stain with carmine. 



(d) Make cross and longitudinal sections of the youngest states of 

 the stems of the pumpkin, squash, and asparagus, and compare with 

 similar sections of older parts. 



36. In the lower plants the cells are all alike, or so 

 nearly so that they constitute but one kind of tissue. As 

 we ascend from these simple forms the cells begin to show 

 differences, some being especially developed for one pur- 

 pose, and some for another; and these differences become 

 more numerous and more sharply marked as we approach 

 the higher plants. This at last gives us many kinds of 

 tissues, which may be distinguished from each other by 

 characters of greater or less importance. However, they 

 may all be brought within seven general kinds, each kind 

 showing many varieties. 



37. Soft Tissue {Parenchyma). — This is the most abun- 

 dant tissue in the vegetable kingdom ; it is at once the 

 most important and the most variable. It is composed of 

 cells whose walls are thin, colorless, or nearly so, and 

 transparent; in outline they may be rounded, cubical, 

 polyhedral, prismatic, cylindrical, tabular, stellate, and of 

 many other forms. When the cells are bounded by plane 

 surfaces, generally, but not always, the end planes lie at 

 right angles to the longer axis of the cells. 



