42 THE MICROSCOPE. 
Selections. 
IMBEDDING IN EcG Mass.—Professor Calberla was the first to 
use successfully the albumen of hens’ eggs as an imbedding medium 
and although the method of procedure has been published for 
several years, American students have not generally availed them- 
selves of its advantages. The modus operandi is as follows: 
The whites of several eggs are carefully separated from the 
yolks and then the fibrous portion known as the chalazez is re- 
moved and the rest cut up with scissors. Fifteen parts of the white 
are now vigorously shaken with one part of a ten per cent. solution 
of carbonate of sodium. The yolk is now added and the shaking 
repeated, and a subsequent filtering removes the bubbles and frag- 
ments of the chalazez, etc. A small paper tray of the usual pattern 
is filled with the resulting fluid and immersed in alcohol which by 
abstraction of the water coagulates the albumen, forming a solid 
block. 
For imbedding, one of these blocks is taken and washed in 
water to remove the alcohol and then dried slightly with blotting 
paper. A small cavity is now scooped out the surfaces of which 
are wet with the fluid egg. The object to be imbedded is likewise 
deprived of alcohol by water and is then placed in any desired 
position in the hollow. Now a drop of alcohol will fasten ‘it firmly 
by coagulation of the fresh egg. The block is now washed again 
and fluid egg is poured over to cover the object. To confine this 
egg it is best to place the object and hardened mass in a box ,and 
then pour in the fluid egg. The box and its contents are then to be 
placed in a vessel and exposed to alcohol steam until the new por- 
tion of egg is coagulated. Various plans for thus steaming the pre- 
paration have been devised. A convenient and simple method em- 
ploys a fruit jar in the bottom of which a little alcohol is poured. 
The box is then placed in the jar and the opening closed with a 
glass funnel. The whole is now heated in a water bath for from thirty 
to forty minutes, care being taken that the alcohol does not boil. 
It is then removed and placed in alcohol which should be changed 
once or twice in the first twenty-four hours. It may then be cut at 
any time or the cutting may be suspended and the object kept in- 
definitely by immersion in alcohol. 
The object to be cut should be stained before imbedding but 
