164 THE AMERICAN MONTHLY [September, 
1. The tissues must be thoroughly dehydrated. 
2. An intermediate bath of paraffine in the solvent must be used to pre- 
vent shrinkage. 
3. The solvent must be completely replaced by pure paraffine. 
4. Dry heat should be used in all the melting processes. 
5. Paraffine with a proper melting point must be used, as it is not safe 
to heat to, or beyond, 60° C. (140° F.) ;_ nevertheless tissue will not be in- 
jured by any temperature which can be borne by the hand. 
6. The section knife must be perfectly free from breaks in its edge, and 
very sharp. 
MYRTLE WAX IMBEDDING PROCESS. 
In an article in the Vew York Medical Record, April, 1885, Dr. Maurice 
N. Miller, of New York, called attention to a new imbedding material which 
he claims possesses some advantages over the paraffine and celloidin processes. 
The material is myrtle wax or bayberry tallow. Myrtle wax is a substance 
derived from Myrica certifera, a shrub from one to twelve feet high, growing 
in the United States, especially along the eastern coast. 
The wax is found covering the fruit as a whitish coat, and is separated for 
use by boiling the berries in water ; the wax separates and rises to the top, and 
is either skimmed off or allowed to concrete as the liquor cools, and is then 
removed. It is of a pale, grayish-green color, somewhat diaphanous, brittle, 
slightly unctious to the touch, and has a feeble aromatic odor and a slightly 
bitterish taste. Its sp. gr. is about that of water, and its melting point is about 
40:0,.C. tos:8C.\(116.b tom 202) 
It is insoluble in water, scarcely soluble in cold alcohol, soluble except about 
13 per cent. in twenty parts boiling alcohol, which deposits the greater part of 
it on cooling. It is also soluble in boiling ether, and slightly so in oil of tur- 
pentine. 
In addition to the above solvents, usually given, I have found it to be very 
soluble in chloroform, benzole, and xylol. 
The wax described above is no doubt the true product of JZyréca certifera, 
but for the purposes of the microtomist it will zo¢ answer. A variety must 
be obtained which is yellow7¢sh whzte in color, tougher and softer. This va- 
riety, though so/d as myrtle wax, is probably the product of Rhus succedanea 
Ln., and should be called ‘ Japan wax.’* With the above exceptions, the 
same description of physical characteristics will answer for both. 
Dr. Miller based his method upon the following facts :—‘ Bayberry tallow 
is firm and solid at ordinary temperatures, and is soluble in warm alcohol.’ 
He claims that specimens may be removed from the alcohol in which they 
have been preserved and placed at once in a bath of melted wax ; but I think 
it is better to first dehydrate in absolute alcohol and then place in a prelimi- 
nary bath of wax dissolved in chloroform. 
Benzole and xylol will dissolve large quantities of the wax, but it is de- 
posited in a granzular form on their evaporation; but on evaporation of the 
chloroformic solution the wax is left in a solid form. Chloroform is, for this 
reason, preferred as a solvent for the preparatory bath, but for all other pur- 
poses the less expensive solvents may be used. 
The chloroform may be used over and over again, and if occasionally a little 
fresh be added to it this bath may be kept always ready. 
* Dr. Z. D. Gilman, of Washington, D. C., informs me that the wax in question is imported through a Japan 
trading company, and is said to be derived from Rhus succedanea, Ln. If this be its source, it is then one of 
the varieties of Fupan wax. 
Dr. Blackburn, in a private letter, desires to add his acknowledgment to Dr. Seaman (see this Yournad, 
p. 138), who determined that the yellow wax, which is the one here referred to, was the product of Aus succ. 
He says :—‘ In view of the present information upon the waxes, it is obviously wrong to continue applying the 
name ‘‘ myrtle wax’’ to the yellow variety, which is the kind used, but as it is sold under that name, and the 
originator of the use of the wax so called it, I shall not alter the name used.’—[Ep. 
