830 General Notes. [ August, 
sections of large objects; and in these sections all loose bits of 
tissue are kept zz stu by the celloidin which does not interfere 
with the staining or mounting. If for any reason it is desired to 
remove the celloidin, a little ether and alcohol will dissolve it 
from the section almost immediately. For the study of loose 
parts, where the sections would otherwise fall to pieces or require 
difficult manipulations, such as the placenta or brain, celloidin 
may, I think, be safely said to surpass any other material hith- 
erto employed. 
For mounting sections with celloidin left on them I have found 
none of the methods hitherto recommended satisfactory. The 
essential oils I have tried either dissolve the celloidin like oil of 
cloves, or cause it to shrink and distort the section like oil of Ber- 
gamot. After trying various reagents, I have settled upon chlo- 
roform as the most convenient medium of transfer from alcohol 
to balsam. In using it care must be taken to place the section 
Microrome Knives.—The Scientific Instrument Company of 
ibridge, England, are preparing an automatic machine for 
sharpening microtome knives, which, it is to be hoped, may prove 
to be just what every microtomist so much needs. 
_ acceptable condition, and sometimes they have been much dam- 
aged or wholly ruined. The best test for the condition of the 
edge is to try it on the palm of the hand. A knife that will not 
-= cuta ribbon of paraffine sections .005™™ thick is not fit to use; 
_ the best knives should cut as thin as .co1r™™ It is not often that 
-it beci irable to cut so thin, but it is important in making 
thick sections ( mm) to use a knife that has a much finer 
cing capacity. A thoroughly sharp blade may have very 
