STAINING AND MOUNTING FROZEN SECTIONS 185 



I inch wide and 2 inches long ; some needles, which may be 

 mounted in handles ; slides, cover-glasses, and balsam. 



A section is to be removed from the bowl of water in which it 

 is floating by means of one of the strips of paper ; this must be 

 inserted under it, and the section " pinned " in place upon it by one 

 of the needles. A special section-lifter may be used, but is not so 

 good. It is then transferred to the watch-glass containing the 

 haematoxylin solution, and the staining process is allowed to go 

 on for a minute or two, a fresh section being manipulated whilst 

 it is taking place. The first section is then removed in the same 

 way as before, and placed in the water containing the ammonia ; 

 it soon turns blue, and when this is the case it is ready to be 

 transferred to the eosin, then into the dilute alcohol, the absolute 

 alcohol (where it should remain for a minute or more), and finally 

 into the oil of cloves. It is then ready to be mounted in balsam. 

 A convenient way in which a section can be transferred to a slide 

 is as follows : The section is carefully spread out whilst in the 

 oil of cloves, two needles being used for the purpose, and a slip of 

 paper insinuated beneath it. This strip of paper is then drawn 

 slowly out of the liquid, and any folds or creases which may be in 

 the section straightened out with the needles, the excess of the 

 oil of cloves being allowed to drop off whilst this is taking place. 

 The strip of paper is then inverted (the section remaining adherent 

 to the under surface), placed upon a clean slide, and pressed firmly 

 upon it ; the pressure squeezes out the greater part of the oil, so 

 that the section adheres to the slide, and the paper can be stripped 

 cautiously from it. A drop of balsam is then applied, the section 

 covered with a cover-glass, and examined under a microscope. 



It is of great advantage to rinse the section in distilled or clear 

 rain-water after removing it from the heematoxylin. 



The solution of haematoxylin is best bought ready made, as its 

 preparation is somewhat difficult. Delafield's solution is the best 

 for general work. 



A counterstain is not really necessary for diagnostic purposes, 

 and its omission hastens the process somewhat. 



THE PARAFFIN PROCESS 



Tissues which are to be cut in paraffin may be hardened in any 

 of the fluids mentioned above. They are then dehydrated, cleared 

 in chloroform or other fluid which mixes with alcohol and dissolves 



