370 PHYTOGRAPHY. 



SECTION IV. SPECIMENS ; DIRECTIONS FOR THEIR EXAMINA- 

 TION, PRESERVATION, &c. 



770. Implements. Those necessary for the examination of 

 })h;vnogamous plants. Ferns, and the like, are a simple pocket 

 lens, a simple dissecting microscope ; also a sharp thin-bladed 

 knife and some needles of various fineness, mounted in han- 

 dles, for dissection. 



771. For a single hand lens, one magnifying only from four to 

 six diameters is the most useful. A doublet, or a parabolic lens 

 of Tolles, of about an inch focus, is better, but much more expen- 

 sive. The simple stage-microscope for dissection need have only 

 two lenses (doubl'ts or otherwise) with large field and good 

 definition, one of an inch and the other of about half inch focal 

 distance: and a glass stage of at least an inch and a half in 

 diameter. A compound microscope is useful for all minute 

 investigation, and is essential in the study of vegetable anatomy 

 and of all lower cryptogamic botany. 



772. For making thin slices, a razor is the best knife ; for dis- 

 section on the stage of the simple microscope, beside needles, 

 small scalpels or some of the cutting instruments used by ocu- 

 lists are very convenient. But an expert hand is able to do 

 almost every thing with a common knife or scalpel and a pair 

 of mounted needles. Slender forceps are almost indispensable : 

 those made for the use of dentists are the best. 



773. Analysis. In the examination of an unknown plant with 

 a view to its determination, its whole structure should be made 

 out, so far as the materials allow, before a step is taken to 

 ascertain its name and place in the S3-stem. In respect to the 

 stem, its duration and consistence and its internal structure, 

 whether exogenous or endogenous, are to be noted. As to the 

 foliage, the venation and the phyllotaxy. also the presence or 

 absence of stipules, are most important. The antkotaxy or 

 inflorescence is to be examined and referred to its proper type. 

 In the llower. the numerical plan and symmetry, its ground-plan 

 and the nature of the deviations from the general or the- family 

 type, are to be considered; also the aestivation or arrangement 

 of the parts in the bud. the character and extent of coalescence 

 and adnation ; the manner in which the anther is borne upon the 

 filament, and its place and mode of dehiscenee. &c. Note also 

 whether, when the blossom is hermaphrodite, the anthers and the 

 stigmas mature at the same or at different periods. The placen- 

 tation and the character and position of the ovules should be 



