MICROSCOPIC PREPARATIONS IN MARINE ZOOLOGY 325 



and object and all will feel like a bit of cartilage. (It can 

 remain in methylated spirit indefinitely.) 



To fix it in the microtome surround it with some melted 

 paraffin-wax. As the wax cools in the well it will very 

 likely leave a little space around the sides, and perhaps 

 around the object, due to uneven shrinkage of the two 

 things. The wax must be only at melting point, or the 

 object will griddle up. If there is a little space, as I have 

 said, warm a wire, and stick it in here and there until every- 

 thing is firm. Small objects are best cemented to a bit of 

 wood for a support, cementing with stiff celloidin, and then 

 hardening in chloroform. 



Now proceed to cut, as previously directed, only the 

 razor must be used so as to draw cut. Cut slowly, yet 

 unhesitatingly. 



If the section is thick at one side and thin at the other, 

 or if the razor passes over once or twice without taking off 

 a section and then takes a thick one, the embedding is 

 faulty : there is something " springy," or else you have 

 altered the angle at which the razor was held. Rectify this. 



There will be many failures at first, but success will come. 

 As the sections are cut they can be put into methylated 

 spirit, and either left for another day or mounted at once. 



To mount them they must first be cleared. Put them / 

 in strongest methylated spirit a little while (not in absolute 

 alcohol., as this dissolves celloidin) ; then transfer them to a 

 little pot, with oil of bergamot. (Oil of cloves dissolves 

 celloidin.) 1 They will clear very slowly, but they can be 

 left in the clearing a long time without injury. When they 



1 A splendid clearing fluid, which does not dissolve celloidin, 

 and which clears any object direct from ordinary methylated 

 spirit, can be prepared thus : Dissolve one ounce of carbolic 

 crystals (absolute phenol) in a mixture of equal parts of the oils 

 of cedar and bergamot, employing gentle heat to hasten the 

 solution. The same quantity, in a little pot, can be used several 

 times over. 



