350 THE MICROSCOPE. 



whereas by the use of the microscope the differences of 

 structure in these two substances, as in many other cases, 

 can be promptly discerned. Out of thirty-four samples of 

 coffee purchased, chicory was discovered in thirty-one ; 

 chicory itself being also adulterated with all manner of 

 compounds. There is no falling back either upon tea or 

 chocolate ; for these seem rather worse used than coffee. 

 Tea is adulterated, not only here, but still more in China ; 

 while as to chocolate, the processes employed in corrupting 

 the manufacture are described as " diabolical." " It is 



Fig. 195. 



1, Radiating cells from the outer shell of the Ivory Nut. 2, Section of a Nut, 

 showing cells with small radiating pores. 



often mixed with brick-dust to the amount of ten per 

 cent., ochre twelve per cent., and peroxide of iron twenty- 

 two per cent., and animal fats of the worst description. In 

 this country, cocoa is sold under the names of flake, rock, 

 granulated, soluble, dietetic, homoeopathic cocoa, &c., fig. 

 191. Such names are evidently employed to disguise the 

 fact that they are compounded of sugar, starch, and other 

 substances. 



To return to the subject more immediately before us 

 Some of the plants belonging to the Orchidese Com- 

 melinece particularly Tradescantia virginica (Spiderwort), 

 portions of the epidermis, and the jointed hairs of 

 the filament, form interesting microscopic objects. The 

 surface of the latter is marked with extremely fine longi- 

 tudinal parallel equidistant lines or striae, whose intervals 

 are equal, from about 15 ^ 00 to 2o j* 0(y of an inch. It 

 might therefore in some cases be used as a micrometer or 

 test object. The nucleus of the joint or cell is very dis- 

 tinct as well as regular in form ; and by gentle pressure 



