SECTION CUTTING. 189 
in a thick and syrupy solution of gum arabic; if time is 
no object it is a great advantage to soak them in this 
for several hours. A block is then placed on the 
corrugated plate of the microtome and frozen by means 
of the ether spray which impinges upon it. When the 
ty Aly 
in 
al 
Fic. 31.—Cathcart’s microtome arranged for cutting frozen sections. 
3: if g 
mass is nearly frozen a section is taken off by means of 
a razor which is ground flat on one side, or the special 
knife which may be obtained with the apparatus: it is 
better to moisten the upper surface of the knife with a 
