184 



BACIEBIOLOGY. 



the cork with the piece of tissue upon it may be left in 

 alcohol over night, and on the following day the sec- 

 tions may be cut. 



Section-cutting. — This is accomplished by the use 

 of an instrument known as a microtome. In Fig. 36 

 is seen the form now commonly employed. It is known 

 as Schanze's microtome. It is an apparatus provided with 

 a clamp for holding the cork upon which the tissue is ce- 

 mented, and also a sliding clamp which carries a knife. 



Fig. 36. 



Schanze's microtome. 



The tissue is clamped horizontally, and the knife is caused 

 to slide across its upper surface, also in a horizontal plane. 

 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 



