822 SUMMARY OF CURRENT RESEARCHES RELATING TO 



change. As in other methods, the water must be previously entirely 

 removed from the preparation, and then it is quite unimportant 

 whether before putting it into paraffin it is placed in turpentine oil or 

 oil of cloves, or, as the author does, into resinous turpentine saturated 

 with paraffin, which must not be too thick. 



Celloidin for Imbedding'.* — The following is the manner of pre- 

 paring and using this material practised in the laboratory of the Alumni 

 Association of the College of Physicians and Surgeons at New York 

 (as given by Dr. G. C. Freeborn). 



A saturated solution of celloidin is made in a mixture of equal 

 parts of ether and 97 per cent, alcohol. This requires about 24 hours 

 with occasional agitation. The object to be imbedded is soaked 

 in a mixture of ether and alcohol for some time, then transferred 

 to the imbedding fluid and allowed to remain overnight. 



One of two ways of imbedding may be adopted : — 



1. Cover the smooth surface of a cork with a thick layer of 

 celloidin solution and allow it to dry ; place the specimen, which 

 has previously been soaked in the imbedding fluid, on this, and cover 

 it, layer by layer, with a solution of celloidin, allowing each layer to 

 partially dry before applying another. When the specimen is com- 

 pletely covered immerse in alcohol of 80 per cent, for twenty-four 

 hours when it will be ready to cut. 



2. The specimens are imbedded in paper boxes in the usual way, 

 or a cork is wrapped with one or two layers of thick writing paper, 

 allowing it to project an inch or an inch and a half above the surface 

 of the cork. By this procedure a round box with the cork for a 

 bottom is obtained. Into this box pour a small quantity of the im- 

 bedding fluid, and allow it to dry. The specimen having been pre- 

 viously soaked in the celloidin solution, is now placed in the box, 

 adjusted as to position and allowed to dry for five or ten minutes, so 

 as to fix it ; the box is now filled with the imbedding fluid. The 

 boxes are exposed to the air until the imbedding mass has become 

 semi-solid, and are then immersed in weak alcohol (alcohol 95 per 

 cent, two parts, water one part) for twenty-four hours, when the 

 specimen will be ready for cutting. If the specimen has been im- 

 bedded in a paper box and sections are to be cut with a sliding 

 microtome, it is necessary to mount it on a cork. This is accom- 

 plished in the following manner : — Cover the surface of a smooth cork 

 with a thick layer of celloidin solution, allow it to dry, and again cover 

 with the same. Trim off the superfluous imbedding mass from around 

 the specimen, cut the lower surface even, wet it with a drop or two 

 of ether, and adapt it to the layer of celloidin on the cork. Dry for 

 a few moments and place in dilute alcohol for a few hours, when the 

 specimen will be ready for cutting. If the plan of imbedding in the 

 boxes with a cork for the bottom is adopted, the specimen is imbedded 

 and mounted on the cork at the same time. 



Sections may be stained with the different staining fluids and 

 mounted in glycerine or other media. If mounted in Canada balsam 



* Amer. Mon. Micr. Journ., v. (1884) pp. 127-8, from New York Med. 

 Journ. 



