54 . W. J. DAKIN. 



This was followed by a rapid washing out in water, dehydra- 

 tion in 90 per cent, alcohol to absolute, and mounting after 

 xylol or origanum oil in balsam. 



Iron haematoxyliu. — The sections were mordanted for 

 twenty-four hours in a 4 per cent, solution of iron alum 

 washed in water, and stained in a 0"o per cent, to 1 per cent, 

 solution (aqueous) of haematoxyliu for twelve to twenty-four 

 hours. This was followed by differentiation under microscopic 

 observation with 2 per cent, iron alum solution. Tap-water, 

 alcohol dehydration, etc., as usual. 



The modified Weigert method was only used after 

 Zenker fixation. It was partly like that used by Schreiner 

 (30), but modified in combination with Zenker. 



Schreiner used a 10 per cent, alcoholic solution of haetna- 

 toxylin (P. Mayer says that the " 10 per cent. " must be a 

 mispriut). 



I used a 5 per cent, solution, but did not investigate the 

 effects of a stronger nor of a 1 per cent, solution, which Mayer 

 believes to be the one intended by Schreiner. 



The sections (on slides) were placed in a 3 per cent, solution 

 of potassium bichromate for twenty-four hours, then rinsed 

 in water and alcohol, and placed in a 5 per cent, solution of 

 haematoxyliu (alcoholic) for a time varying from ten minutes 

 to an hour. The sections must be black, and this takes place 

 much quicker after the haematoxylin solution has been used 

 once or twice and is oxidised by contamination with bichro- 

 mate. After staining, the sections were rinsed in water and 

 placed in a saturated aqueous solution of copper acetate, 

 which turns them a steel-blue colour. Differentiation was 

 carried out (under microscopic observation) in the following 

 solution : 



Borax 2*0 gr. 



Pot. ferricyanide . . . . . 2*5 gr. 



Distilled water lOO'O c.c. 



The sections wei'e then washed in tap water and mounted 



in the usual way, after alcohols and xylol, in Canada-balsam. 



Picric acid — saurefuchsin (van Gieson). — The sections 



