STAINING AND MOUNTING FROZEN SECTIONS 2IQ 



be used, but is not so good. It is then transferred to the 

 watch-glass containing the hsematoxylin 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 trans- 

 ferred 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 hsematoxylin. 



The solution of hsematoxylin 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 pur- 

 poses, 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 paraffin, and finally soaked in a 

 mixture of hard and soft paraffin kept just at the melting- 



