160 
NOTES AND MEMORANDA. 
bowl, holding a quart ; a small tin strainer. This is the least possible 
outfit for preparing the tissue in question. The remaining appliances 
for mounting are pre-supposed. Pick the leaf with care (one, say, a 
half or three-fourths inch long), handling it always by the stem end, 
and with tenderness, so that pubescence of any kind may not be lost, 
and the epidermis receive no bruise. Put the leaf in water for two or 
three hours ; then into common alcohol for about the same length of 
time ; then into a morphia vial, into which pour of Labarraque’s 
solution enough to well cover the leaf, corking closely. At intervals 
of a few hours gently shake the vial. As soon as the chlorophyll has 
disappeared, which, according to the nature of the leaf, will take place 
in from two hours to seventy-two, remove the leaf to about a pint of 
clear, cold water. This water should be changed every three or four 
hours, and the leaf kept in for at least twenty-four hours, and at most, 
forty-eight. For example, an Aucuba japonica, or a Magnolia grandi- 
Jlora, should, because of their density, remain in the water forty-eight 
hours, with five or six changes. The thinner and less dense leaves, as 
Momordica balsamia, oxalis, or drosera, should not lie longer than 
twenty-four hours. The leaf being washed, it is placed in common 
alcohol in a jar, enough to cover it. In this it remains for twenty- 
four hours. After an immersion of one hour in fresh alcohol it is 
ready for the dye. Sections of leaf, petiole, or twig, require from two 
to twelve hours in the solution. They may be removed when the 
natural colour is gone. If they contain much thickened cells, they 
may remain five or six hours longer. Sections are washed just like 
leaves, not needing, however, so many changes. Being cleansed of 
the solution, they are placed in common alcohol for several hours ; 
then into absolute alcohol for at least one hour. If very open in 
structure, like the Pontederia, they should lie four or five hours in 
absolute alcohol. Single Staining. — For a single colour, logwood is 
probably the best. That prepared according to Arnold’s formula, 
being redder, is most satisfactory. A small quantity is poured into a 
jar. The object is immersed for two or three minutes in alum water, 
then placed in the dye, where it remains, until, on lifting it out, it is 
found to have quite a dark hue. It is then removed to clear, cold 
water for ten minutes ; then change the water, carefully brushing the 
object with a camel’s-hair brush ; then remove to common alcohol for 
two hours ; after that to absolute alcohol for one hour ; to oil of 
cloves, until, on holding it to the light, it scintillates in every part. 
Then mount in balsam. 
This is the formula for preparing the carmine dye: 
Carmine 24 grains 
Aqua ammonia 72 drops 
Water 4 ounces 
Alcohol 8 drachms 
Pulverize the carmine ; put in a test-tube ; add the ammonia ; 
bring twice to boiling point. Set aside for twenty-four hours, 
uncovered, to allow the ammonia to evaporate ; add then the water 
and alcohol, and filter. Before putting the object in the dye, dip it 
for a few seconds in water. To obtain the proper depth of hue, the 
