400 MANIPULATION. 



VEGETABLE TISSUES. 



Preparations of vegetable tissues are principally obtained 

 either by tearing, by making sections, by maceration, or by 

 dissection, whilst others can be examined in the natural state. 



Cuticles. — The cuticle of the stem, flower, or leaves, may be 

 removed in the manner described at page 353, by taking a 

 small portion between the blade of the knife and the thumb, 

 and tearing it away in the direction in which the separation 

 is most easily effected. Cuticles should be mounted either 

 dry or in fluid ; when much colouring matter is present, the 

 former method, or that in balsam, should be adopted. A few 

 of the most illustrative specimens may be obtained from the 

 following plants : — 



Siliceous Cuticles. — These, obtained from the following stems 

 and parts of grasses in the manner before described at page 333, 

 by the action of acid, wiU exhibit the beautiftil arrangement of 

 silica so constant in this tribe of plants, which forms so 

 splendid an object for polarized light : — ■ 



"With the above list may be included the foUovnng one, 

 which consists of the hairs from the leaves of certain plants ; 

 these, like the cuticles above described, are provided with a 

 protecting coat of silica : — 



Deutzia, Durio Eteagnus, Olive. 



Hairs. — These are found principally upon the under surfaces 

 of leaves, upon stems, or upon some part of the flower ; they 

 are generally viewed as opaque objects ; some of the larger 



