SECTION CUTTING WITH THE STIRLING MICROTOME. 



13 



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

 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. 5. 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 vaseline, and heat until thoroughly mixed. 

 The microtome having been previously warmed standing upright, 

 is filled with the imbedding mixture. The piece of tissue is then 



FIG. 5. MANNER OF CUTTING AND ARRANGING PIECES OP PITH, TURNIP, ETC., FOR SUPPORTING 

 HARDENED TISSUE IN THE WELL OF A MICROTOME. 



carefully wiped dry with the blotting paper and, just as the imbedding 

 begins to congeal around the edges, is pressed below the surface with 

 a needle and held until the cool mixture fixes it in position. The 

 whole is now allowed to become thoroughly cold. By turning the 

 screw, the plug of wax is raised ; and it must be gradually cut away, 

 by sliding the knife across the plate, until the upper part of the 

 tissue appears. 



Before commencing to cut sections however the tissue may have 

 been imbedded provide yourself with a saucer of alcohol and a 

 camel's-hair pencil. Having wetted the knife, turn the screw so that 

 the tissue, with its imbedding, appears slightly above the plate of the 

 microtome ; and then, resting the blade of the razor on the plate 



*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. 



