SECTION 19.] INVESTIGATION AND DETERMINATION. 187 



3. INVESTIGATION AND DETERMINATION OF PLANTS. 



570. The Implements required are a liaud magnifying glass, a pocket 

 lens of an inch or two focus, or a glass of two lenses, one of the lower 

 and the other of the higher power ; and a sharp penknife for dissection. 

 With these and reasonable perseverance the structure of the flowers and 

 fructification of most phanerogamous plants and Ferns can be made out. 

 But for ease and comfort, as well as for certainty and right training, the 

 student should have some kind of simple stage microscope, and under 

 this make all dissections of small parts. Without it the student will be 

 apt to fall into the bad habit of guessing where he ought to ascertain. 



571. The simple microscope may be reduced to a good lens or doublet, 

 of an inch focus, mounted over a glass scage, so that it can be moved up 

 and down and also sidewise, and with (or without) a little mirror under- 

 neath. A better one would have one or two additional lenses (say of half 

 and of a quarter inch focus), a pretty large stage, on the glass of which 

 several small objects can be placed and conveniently brought under the 

 lens; and its height or that of the lens should be adjustable by a rack- 

 work ; also a swivel-mounted little mirror beneath, which is needed for 

 minute objects to be viewed by transmitted light. 



572. For dissecting and displaying small parts on the stage of the 

 microscope, besides a thin-bladed knife, the only tools needed are a good 

 stock of common needles of various sizes, mounted in handles, and one or 

 more saddler's-needles, which, being triangular, may be ground to sharp 

 edges convenient for dissection. Also a pair of delicate-pointed forceps ; 

 those with curved points used by the dentist are most convenient. A 

 cup of clean water is indispensable, with which to moisten or wet, or 

 in which occasionally to float delicate parts. Small flowers, buds, fruits, 

 and seeds of dried specimens can be dissected quite as well as fresh ones. 

 Tney have only to be soaked in warm or boiling water. 



573. The compound microscope is rarely necessary except in crypto- 

 gamic botany and vegetable anatomy ; but it is very useful and convenient, 

 especially for the examination of pollen. To the advanced botanist it is a 

 necessity, to all students of botany an aid and delight. 



574. Analysis. A few directions and hints may be given. The most 

 important is this : In studying an unknown plant, make a complete ex- 

 amination of all its parts, and form a clear idea of its floral structure 

 and that of its fruit, from pericarp down to the embryo, or as far as the 

 materials in hand allow, before taking a step toward finding out its name 

 and relationship by means of the keys or other helps which the Manuals 

 and Floras provide. If it is the name merely that is wanted, the shorter 

 way is to ask some one who already knows it. To verify the points of 

 structure one by one as they happen to occur in an artificial key, without 

 any preparatory investigation, is a usual but is not the best nor the surest 



