We have endeavoured to figure only such tissues or elements, 

 fragmentary or intact, as by their distinctive features or constant 

 occurrence offer important and easily detected characters. We 

 have avoided the reproduction of the various minute particles 

 which, being found in many powders, do not assist in distinguish- 

 ing one from the other. If the illustrations lack the artistic 

 appearance of those in other similar works they are at least clear 

 and accurate. Most of the drugs described are official in the 

 British Pharmacopoeia ; those that are not, together with various 

 starches, flours, etc., have been introduced to make the work more 

 generally useful. 



We trust that students of this fascinating subject will appreciate 

 the object we have had in view, and welcome a work designed to 

 guide them in one of the most intricate of their studies. 



HENRY G. GREENISH. 

 EUGENE COLLIN. 



