SECTION-CUTTING. 157 



farther from the plane in which the knife slides. By 

 this arrangement sections of any desired thickness can 

 be cut by turning the milled disc with the one hand and 

 causing the knife to traverse the tissue with the other. 



FIG. 32. 



Schanze's microtome. 



The tissue and the knife-blade should be kept wet 

 with alcohol, so that the sections may float upon the blade 

 of the knife, from which they can be easily removed 

 without tearing, with a curved needle or a camel-hair 

 pencil. As the sections are cut they are placed in a dish 

 containing alcohol. 



There are some tissues which, by reason of their his- 

 tological structure, do not become sufficiently dense when 

 exposed to alcohol to permit of their being cut in the 

 above way. It becomes necessary to render them more 

 solid by filling their interstices with some substance that 

 neither interferes with their structure, nor prevents their 



8 



