146 



BACTERIOLOGY. 



Beneath the clamp for holding the tissue is a milled 

 disk, by means of which a screw is caused to revolve, 

 and in revolving raises or lowers the clamp holding the 

 tissue, so that the tissue may be brought closer to or 

 farther from the plane in which the knife slides. By 

 this arrangement sections of any desired thickness can 

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

 causing the knife to traverse the tissue with the other. 



Fig. 31. 



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 



