696 PHARMACEUTICAL BOTANY 
alcohol for 12 hours to pure xylol for 12 hours. To phial con- 
taining material in pure xylol add paraffine in small pieces and 
put on top of paraffine bath sufficiently long until paraffine is 
melted. Then add more paraffine and put phial in paraffine 
bath at 56°C. over night. Pour fluid off and add pure melted 
paraffine and repeat 2 or 3 times until rid of all trace of xylol. A 
tray is then prepared by taking a piece of paper and folding up 
its edges all around to the height of about a half inch. Half fill 
this on a cool surface with melted paraffine. Heat two dissection 
needles in bunsen flame and with these dispose pieces of material 
in orderly fashion over the crust which has by this time formed at 
the bottom of the tray. Blow upon the surface of the paraffine to 
harden it more quickly and as soon as the surface crust will bear 
it, plunge the tray into cold water. The material can now be 
left imbedded in paraffine until required for sectioning. 
If cutting is to be done in a cool room, softer grades of paraffine 
with melting points between 40° and 50°C. should be used for 
imbedding. If, on the other hand, cutting is to be done at sum- 
mer temperatures, the harder grades melting at between 55° and 
70°C. should be employed. 
Use or N-BpuTyYL ALCOHOL IN [MBEDDING Woopy PLANT ORGANS 
This method, originally devised by Dr. Conway Zirkle, is 
designed to eliminate the hardening and shrinking of tissues 
induced by the ethyl alcohol and xylol used in the common 
procedure of paraffin embedding. While the common method, 
heretofore described, is suitable for the softer plant materials, it is 
unsuited for plant materials containing abundant lignified 
elements. The higher concentrations of ethyl alcohol and the 
xylol so harden the woody elements that they are almost impos- 
sible to cut, but break and chip the microtome knife. 
Woody plant organs or tissues may be dehydrated and cleared 
with a mixture of ethyl and N-butyl alcohols, eliminating the . 
use of the higher ethyl alcohols and xylol. N-butyl alcohol dis- 
solves sparingly in water but in all proportions in paraffine. A 
mixture however of equal parts of ethyl and butyl alcohols is 
completely miscible with water. By substituting butyl alcohol 
for xylol, the processes of dehydration and paraffine infiltration 
