SECTION CUTTING WITH THE MICROTOME 13 



instruments is seen in Fig. 5. The Stirling microtome consists 

 essentially of a short brass tube, into which the tissue is fixed 

 either by pressure or by imbedding in wax. A screw enters below, 

 which, acting on a plug, raises the contents of the tube. As the 

 material to be cut is raised from time to time by the screw, it 

 appears above the plate which surrounds the top of the tube. 

 This plate steadies and guides the razor ; and it is evident that 

 more uniform sections may be cut with this little apparatus than 

 'would be possible with nothing to support the knife, or to regulate 

 thickness, beyond the unaided skill, of the operator. 



Much depends upon the manner in which the material is fixed 

 in the tube or well of the microtome. If the tissue be of a solid 

 character, like liver, kidney, spleen, many tumors, etc., it may be 

 surrounded with some carefully fitted pieces of elder-pith,* carrot, 



FIG. 6. MANNER OF CUTTING AND ARRANGING PIECES OF PITH, TURNIP, ETC., FOR 

 SUPPORTING HARDENED TISSUE IN THE WELL OF A MICROTOME. 



etc., and the whole pressed evenly and quite firmly into the well. 

 A small piece of tissue which, by cutting, can be made somewhat 

 cubical in shape, may be surrounded by slabs of pith, carrot, or 

 turnip, shaped as in Fig. 6. Indeed, the fragments of imbedding 

 material can be shaped so as to fit tissue of almost any form. 

 Before the whole is pressed into the well of the microtome, the 

 bottom, against which the brass plug fits, should be cut off square. 

 The wax method of imbedding is employed with tissues such as 

 brain, lung, soft tumors, etc., which might be injured by the 

 previous treatment. To three parts of paraffin wax (a paraffin 

 candle answers perfectly) add one part of vaselin, and heat until 

 thoroughly mixed. The microtome having been previously warmed 

 standing upright is filled with the imbedding mixture. The 



"The pith from the young shoots of Ailantus glandulosus (improperly called "Alanthus"), 

 gathered in early autumn, is the best material for this method of imbedding with which I am. 

 acquainted. The wood is easily cut from the pith, and the latter is very large and firm. 



