Preparation of Sections 127 



which is kept at a temperature somewhere near 35° C, and 

 remain there over night. After rinsing in distilled water they 

 are transferred to Weigert's haematoxylin (10 c.c. 10% 

 haematoxylin in absolute alcohol +90 c.c. distilled water + 

 1 c.c. saturated solution of lithium carbonate), again upside 

 down, in which they are kept for 4-6 hours. Following 

 another rinsing, the sections, which are now deep blue or 

 blue-black, are subjtected to the action of Weigert's decolor- 

 izer, a fluid composed of equal parts of a 2% solution of 

 borax and a 2.5% solution of potassium ferricyanide. This 

 mixture is used freely until the desired differentiation is 

 obtained, which may be in a short time or may not be for 

 several hours. 



The differentiating fluid of Pal (equal parts of 1% oxalic 

 acid and 1% potassium sulphite solutions used after a brief 

 immersion in 0.25% potassium permanganate) is very much 

 more rapid and may give more brilliant results, but is less 

 easily controlled in its action. 



The sections are finally washed in running water for 

 twenty-four hours and mounted in Canada balsam. 



Suitsu recommends as particularly suitable for the rat 

 brain a modification of the very similar Kultschitzky techni- 

 que, the description of which may be found in his paper in the 

 Journal of Comparative Neurology, vol. 32, pp. 36-37. 



