112 METHODS OF MICROSCOPICAL RESEARCH. 



sary to this process, whilst a set of cork cutters, 

 or of brass tubes sharpened at one end, must be 

 provided ; one of these tubes must be of the 

 exact diameter of the well of the microtome, and the 

 others, progressively, of smaller diameters, so that 

 the various diameters of the specimens may be 

 matched. A sound carrot must be chosen and a 

 cylinder cut out of its centre, with the largest tube, 

 precisely to fit the well of the microtome, and of the 

 same length as the depth of the well ; now, with a 

 knife divide this cylinder into two equal halves, 

 place the two halves together, and with the tube 

 nearest in size to, but slightly smaller than, the 

 specimen to be embedded cut out the exact centre 

 of the cylinder; this will give two semi-circular 

 pieces of carrot each with a semicircular groove, 

 in one of which place the specimen, lay the other 

 piece upon it, and the specimen is embedded in a 

 cylinder fitting tightly into the well of the microtome, 

 and sections can be cut, after practice, of a great 

 degree of thinness, and without difficulty. 



Embedding in Pith. This substance is used 

 in the same manner as the carrot. A cylinder of 

 pith exactly the size of the well of the microtome 

 is divided longitudinally into two equal halves, and 

 the specimens embedded between the two halves, 

 and if possible without the removal of any of the 

 central pith. Pressure and "kneading" will 

 generally be found sufficient to form a central tube, 

 in which the specimen can be enclosed, with the 

 advantage that no portion of the pith having been 

 actually removed, the cells displaced by pressure 

 will to a great extent recover their original position 

 and exert the desired central pressure and give 



