THE PARAFFIN METHOD 
119 
Shake well and filter through cheese-cloth. It will keep from 2 to 
6 months, but, to say the least, it is never better than when first made 
up. Of course, white of egg may be used alone, since the other two 
ingredients are merely incidental. Put a small drop of fixative on 
the slide, smear it evenly over the surface, and then wipe it off with 
a clean finger until only a scarcely perceptible film remains; then 
add several drops of distilled water and float the sections or ribbons 
on the water. Warm gently until the paraffin becomes smooth and 
free from wrinkles. Wrinkled or curved ribbons may be straightened 
by touching with a needle at each end and pulling gently, just as the 
ribbon begins to smooth out in the warming. Be careful not to melt 
the paraffin, for the albumen of the fixative coagulates with less 
heat than is required to melt the paraffin. If the paraffin should 
melt, run some cold water under it, and transfer the ribbon to another 
slide, prepared with fixative and water. It is a very good plan to 
put the slide on a metal bath or warming plate, like that shown in 
Figure 11. After the sections have become smooth, remove the 
surplus water and leave them on the bath with a couple of thicknesses 
of blotting paper under them for 3 or 4 hours, or, better, over night. 
If the fixative is used alone, as is often the case when sections are 
very thick, none of the delay is necessary, since the sections are 
merely laid upon the fixative and pressed down gently with the 
finger. 
Land’s Fixative.—Mayer’s fixative is so easily prepared and it 
keeps so well that it is in universal use; but, in many cases, it will 
not hold the section to the slide. Moss archegonia and moss capsules 
are likely to wash off, especially if cut rather thick. Large sections 
of cones of conifers are almost sure to float off as soon as the slide 
comes into the xylol or alcohol. Sections of ovules of cycads, as 
soon as they attain a length of 1.5 to 2 cm., are likely to wash off. 
For handling these more difficult cases, Dr. Land devised a fixative 
which has proved satisfactory, even in such extreme cases as sections 
of ovulate cones of Pinus Banksiana 2 cm. long. Formula: 
Gum arabic. 1.0 g. 
Bichromate of potash. 0.2 g. 
Water. 100.0 c.c. 
The mixture will not keep; the formula is given merely to indicate 
its composition. Make a 1 per cent solution of gum arabic in water, 
