3 o6 COLLODION METHOD \_CH.X 



and partly by that which soaks through the paper. It is well to 

 change the chloroform at least once. The used chloroform will con- 

 tain some ether- alcohol, but is good for killing animals. 



FIG. 246. Microtome for collodion sectioning. A microtome of this form 

 may also be used for paraffin sectioning. In that case the knife is set at right 

 angles in order to cut the block square across instead of ivith a drawing cut as 

 for collodion. (Cut loaned by the Bausch & Lomb Optical Co.). 



After 24 or 48 hours the collodion should be firm all through. 

 Then it is placed in 67% alcohol where it may be left a day or 

 more. If it is to be left an indefinite time the 67% alcohol should 

 be changed for 82%. 



457- Sectioning by the Collodion Method. For this 

 one can use a table microtome (Fig. 229) or one of the sliding 

 microtomes (Figs. 246, 247). The sections are made with a knife 

 set obliquely and hence with a drawing cut. 



The holder with the small piece of tissue is clamped in the 

 microtome and arranged as desired, then the sections are made with 

 an oblique knife which is kept wet with 82% alcohol. The best 

 way to keep the knife wet is to have a dropping bottle over the 



