434 Mr Gustav Mann on a Method of 



Method D — continued. 



gently to hasten the mixing of the paraffin, 

 which will be in the upper layers, with the 

 chloroform. Continue till no more paraffin 

 dissolves. [Tissue which did not sink in pure 

 chloroform will always sink as soon as paraffin 

 is added.] 



2. Place the tissue in a warm chamber heated to 



30° C. for twenty-four hours. 



3. Place the tissue in a warm chamber heated to the 



melting point of the paraffin (46° C), and after 

 six hours replace the ordinary cork stopper 

 (which up to this stage has always to be 

 employed) by a perforated one. This method 

 is adopted to ensure a gradual giving off of the 

 chloroform, for I find that, if the latter be 

 driven off rapidly, a good deal of shrinkage 

 always results. When all the chloroform 

 has evaporated, i.e., if after shaking the bottle 

 gently one is unable to detect by smelling the^ 

 faintest trace of chloroform, then the tissue is 

 ready for sectioning. [If the bottle be not 

 shaken gently before smelling the solution, it 

 is often impossible to detect chloroform, 

 although a large quantity of the latter is still 

 in the lower layers of the paraffin, as the upper 

 layers part more readily with the chloroform.] 



4. The tissues should not be exposed longer than 



just necessary to the temperature of melted 

 paraffin, but should be imbedded by means of 

 Leuchart's type-metal box, or by two L-shaped 

 pieces of metal running in an oblong box, the 

 breadth of which correspond to the short limb 

 of the L. The metal boxes should be warmed 

 and filled with melted paraffin. After five to 

 twenty seconds, when the paraffin at the 

 bottom of the box has solidified, the tissue is 

 removed from the bottle by a copper lifter, and, 

 without being allowed to cool, it is dropped 

 into the imbedding box, put into any desired 

 position by means of hot needles, and the 

 paraffin cooled very gradually. It is best not 

 to touch the tissue by any instrument till it is 



