402 MANIPULATION. 



In the Elaters of Jungermanniffi a similar kind of tissue may 

 also be seen. 



Contents of CeZZs.— These consist principally of colouring 

 matter, starch, raphides, liquid and concrete oils, &c., &c. 



Colouring Matter. — Examples occur in the following plants : 



Cuticle of Balsam, Cuticle of Rhubarb, 

 Pelargonium, Salvia. 



Starch. — The granules of starch are obtained from a variety 

 of plants by repeated washing in cold water ; many kinds are 

 sold, but those from wheat, rice, arrow-root, potato, and tons 

 les mois (Canna), are amongst the most common ; the speci- 

 mens should be mounted dry, in a very thin glass cell, or in 

 one made of paper, so as to keep the cover from pressing too 

 much on the granules. A knowledge of the appearance of 

 the different kinds of starch, when examined by the micro- 

 scope, is of great importance in detecting the frauds often prac- 

 tised on the public by introducing granules of our common 

 plants, and pufEng them off as belonging to the more 

 nutritious and expensive kinds ; they are also very beautiful 

 objects when viewed by polarized light. The following list 

 will give the most interesting varieties : — 



Arrow-root, Indian Bean, Sago, 

 — — East Indian, Indian Com, Tapioca, 

 West Indian, Potato, Tous les mois (Canna), 



Iceland Moss, Rice, Wheat. 



Raphides. — These are crystaUine bodies found in the in- 

 terior of the cells of plants ; sometimes they resemble needles 

 in shape (hence their name), at other times they occur in 

 octohedrons, or in stellate bundles. Several varieties wUl be 

 found in the following list : — 



Spiral Vessels. — These may be procured either by macera- 

 tion and subsequent dissection, or by vertical sections of the 



