IN TB OD UCTION. 3 



to their relationships, and upon the basis of such relationships 

 are enabled to classify them or unite them into groups so as 

 to indicate the degree to which they are related. This con- 

 stitutes the division of Botany usually known as Classification 

 or " Systematic Botany." 



Finally, we may study the functions or workings of an 

 organism : how it feeds, breathes, moves, reproduces. This is 

 "Physiology," and like classification must be preceded by a 

 knowledge of the structures concerned. 



For the study of the gross anatomy of plants the following 

 articles will be found of great assistance : 1, a sharp knife, 

 and for more delicate tissues, a razor ; 2. a pair of small, fine- 

 pointed scissors ; 3. a pair of mounted needles (these can be 

 made by forcing ordinary sewing needles into handles of pine 

 or other soft wood) ; 4. a hand lens ; 5. drawing-paper and 

 pencil, and a note book. 



For the study of the lower plants, as well as the histology 

 of the higher ones, a compound microscope is indispensable. 

 Instruments with lenses magnifying from about 20 to 500 

 diameters can be had at a cost varying from about $20 to $30, 

 and are sufficient for any ordinary investigations. 



Objects to be studied with the compound microscope are usu- 

 ally examined by transmitted light, and must be transparent 

 enough to allow the light to pass through. The objects are 

 placed upon small glass slips (slides), manufactured for the 

 purpose, and covered with extremely thin plates of glass, also 

 specially made. If the body to be examined is a large one, 

 thin slices or sections must be made. This for most purposes 

 may be done with an ordinary razor. Most plant tissues are 

 best examined ordinarily in water, though of course specimens 

 so mounted cannot be preserved for any length of time. 1 



In addition to the implements used in studying the gross 

 anatomy, the following will be found useful in histological 



1 For the mounting of permanent preparations, see Chapter XIX. 



