METHODS, 7 



the size and shape of the specimen, is made ; we fill the bottom 

 with a melted mixture of paraffine and wax, six or eight parts 

 of the former to one of the latter, with the addition, perhaps, of 

 a little mutton-tallow. As soon as the layer of the mixture in 

 the box becomes cloudy, the specimen, from which the surplus 

 of alcohol meanwhile was allowed to evaporate, is transferred 

 into the box, and the paraffine mixture, not too hot, is poured 

 over it. The box, when full, is placed in cold water, where the 

 surrounding paper is destroyed, and the fat becomes hard in a 

 short time. The sections are made simultaneously through the 

 paraffine and the specimen, in the same way as described before. 

 No clearing re-agents, such as turpentine or oil of cloves, should 

 be used before imbedding the specimen, as such re-agents render 

 the details of the structure indistinct. Small specimens may be 

 ntted into two pieces of the best so-called velvet-cork, properly 

 hollowed out, and cut together with the cork. 



Everybody can learn to cut sections by more or less practice, 

 though a certain amount of cleverness and steadiness of the 

 hands is required to reach perfection. The rule is, that the 

 section should be very thin, transparent, while its size is of much 

 less importance. Valuable specimens, of which very little ought 

 to be lost, may be cut with a section-cutter. The simplest style 

 is a metal tube mounted at right angles with a circular black- 

 glass or India-rubber plate. The central perforation of the plate 

 opens into a cylindrical metal box of varying diameter, which, 

 by means of a screw, slides within the metal tube. The paraffine 

 mixture is poured into the metal box, and the imbedded speci- 

 men is gradually lifted to the level of the plate, over which the 

 flat surface of the razor-blade is passed. Complicated cutting- 

 machines, in which the blade of the knife works on the principle 

 of a plane, are invented in large number, and prove to be 

 satisfactory in the hands of their inventors, or whenever a large 

 number of specimens is required for distribution or for trade. 

 The greater the complication, the less is the value of such 

 machines. 



Mounting. The sections, after being stained, are transferred 

 on a metal spoon with the assistance of a needle. The best 

 spoon for the purpose is one made of hammered copper wire, the 

 flattened and rounded extremity of which is at a right angle to 

 the wire, the latter constituting the handle. Perforations of 

 the spoon are superfluous. The surplus water is soaked away 

 from the lower surface of the spoon by means of good white 



