23. 



CUTTING AND MOUNTING TISSUES. 



CaCl* 



Fig. 3. Ether wash-bottle for blowing ether vapor upon collodion or celloidin 

 sections to fasten them to slide. The tube of calcium chloride 

 (CaCZj) is for dehydrating the ether vapor. 



collodionized as first suggested by Dr. Mark. This is done by coat- 

 ing the tissue before each section is cut, with a thin coat of one per 

 cent, collodion, using a camel's hair brush for the purpose ; then 

 draw the .knife across the tissue very slowly, keeping alcohol 

 dripping on it while the section is being cut. In this way beauti- 

 ful sections can be obtained of material with loose parts, where all 

 will retain their proper position. Care should be taken that none 

 of the sections be cut before collodionization, for although it may 

 not always be necessary to keep the parts in place, yet it is a safe- 

 guard against their displacement. 



The method given is found to work admirably on very delicate 

 meristematic tissue. No heat being required, the most delicate of 

 tissues will not shrink. The shortness of the method commends it 

 for general use. Two days, or even less, is sufficient to go through 

 the whole operation of hardening, infiltrating, and sectioning, near- 

 ly all kinds of plant tissues. 



The sections after being cut can be easily handled with a 

 camel's hair brush without fear of breaking. 



