P72 APPENDIX ON PRACTICAL WORK. 
action by turning a screw at the back of the tube frame. A good light 
is, of course, necessary. Now remove the low power and follow the 
same course with the high one. A higher magnification can be effected 
by pulling out the inner part of the microscope tube further than the 
groove. 
‘i (2.) Objects when viewed by transmitted light require more elaborate 
treatment, and the following additional apparatus will be required :— 
(a.) A razor for section cutting. A shilling army-razor will answer 
perfectly well. (b.) Some pieces of elder pith. (c.) Half a dozen watch- 
glasses. (d.) A small camel’s-hair brush. (e.) Half a pint of methylated 
spirit, an 8-02. bottle of glycerine, and the following reagents put up in 
I-0z. phials, through the corks of which pieces of glass rod are passed 
(any chemist will do this) :— Dilute glycerine (half glycerine, half water), 
iodine solution (dilute the liquor iodi of chemists to a dark-sherry colour), 
magenta solution (Judson’s magenta dye diluted to port-wine colour), 
caustic potash solution (five per cent.), and strong sulphuric acid. 
Take, for example, a small piece of a delicate leaf treated with chloral 
hydrate, a daisy floret torn open, some pollen, or a bit of epidermis 
pulled from the lower surface of a geranium leaf. Now, with a glass 
rod place a small drop of dilute glycerine in the centre of a slide, put 
the object in the drop, and cover with a cover-glass. One edge of this 
should first be made to touch the slide, and the glass then gently lowered 
with a mounted needle. Now proceed as before, but, in addition, turn 
the mirror so as to reflect light upwards through the olject. N.B.— 
Perfect cleanliness is necessary in all microscopic work. The microscope 
lenses should be kept clean with a piece of new wash-leather, while 
cover-glasses are cleansed by rubbing them gently with a piece of old 
silk between the thumb and forefinger. Of course they should first be 
washed in water if smeared with glycerine, &c. 
Transmitted light is most useful for thin sections of root, stem, leaf, 
anther, ovary, &c. These should be preserved in methylated spirit, and 
placed in a half and half mixture of this and glycerine for twenty-four 
hours before required. Small objects may be held in a slit in a piece 
of elder pith, while leaves can be rolled up. There is no royal road to 
section cutting, and nothing but practice will give the requisite skill. 
A few hints may, however, prove useful. Hold the object firmly in the 
left hand, and, grasping the middle of the razor firmly with the right, 
its edge away from you, make a steady diagonal sweep from the base of 
the blade. Do not push or saw. The razor should be kept wet with 
water for fresh objects, with spirit for spirit specimens. With a sharp 
razor the weight of the blade should be sufficient to carry it through if 
a slight swing is given. Many prefer to cut towards them, using the 
first finger of the left hand asa support for the razor-blade. A number 
of sections should be made, and placed in a watch-glass containing dilute 
glycerine. From this the thinnest can be picked out with the brush and 
mounted as before. A piece of black paper placed beneath the watch- 
glass will enable the sections to be seen more clearly. Do not be con- 
tented till your sections are so thin that the cover-glass will le quite 
flat, and so transparent that all the details can be made out with the 
high power. 
In many cases sections are made clearer by staining, since different 
elements are affected differently. This process is conveniently effected 
