2 54 



PREPARATION OF SECTIONS 



water. If it is desired to keep the sections in the serial order 

 in which they were cut they may be transferred one by one into 

 small phials, a single section to a phial. 



More elaborate microtomes have devices for carrying the section 



knife, or for holding the knife stationary 

 while the object is made to vibrate back 

 and forth against it, and in this way sec- 

 tions can be cut with increased rapidity 

 and accuracy. In some forms there is an 

 automatic feed which can be set to any 

 desired thickness of section. One of the 

 simpler forms of microtomes with a knife 

 carrier is seen in Fig. 143, where the 

 principle of its operation will quickly be recognized. As there 

 shown the knife should be set at an angle to make a long sliding 

 cut in all cases excepting where material imbedded in paraffin is 

 to be sectioned. In the latter event the knife is to be set 

 square across at right angles to the direction of its motion, so 

 that the sections are chopped instead of whittled off. In this 



Fig. 140. — Showing how 

 to trim a block for cutting 

 longitudinal sections. 



Fig. 141. — Simple microtome for clamping to table. P. P. plate glass ways for the 

 section knife; S, milled-head for clamping the object; M, micrometer milled-head for turning 

 the screw that raises the object as the sections are cut; C, milled-head for clamping the 

 microtome to the table. 



