65G H. M. WOODCOCK. 



(2) A 1 per cent, aqueous solution of methylene-bliie 

 (Hochst — an essential point), to which 5 per cent, of pure 

 sodium-carbonate is added. This solution is kept warm at a 

 temperature of 40° to 45° C. for a couple of days or so, 

 when it is made up, after which it is ready for use. 



(3) A 2 per cent, solution of eosin (also Hochst). 



In using- the stain, I have found that a mixture made up in 

 the following proportions gives very good results^ : four drops 

 of each of the three solutions are added to 10 c.c. of distilled 

 water. The different liquids are poured from small drop- 

 bottles of equal size, the drop-bottles being the same as are 

 generally used for Giesma. (The di'ops themselves of the 

 different liquids are not, it may be noted, of the same size.) 



By this method cultural forms are excellently stained in six 

 to eight minutes ; and if any stain is deposited in the ground- 

 substance it comes away readily with orange-tannin after- 

 wards. In fact, on a good smear of cultural forms thus 

 stained, it is often scarcely apparent macroscopically that 

 there is anything at all on the slide. For staining trypano- 

 somes in the blood, only forty to fifty minutes is required. 



In all cases, whichever method of staining was used, the 

 slide was well rinsed with tap-water after staining, and then a 

 few drops of orange-tannin were poured on the slide for half 

 a minute or so, to remove the excess of stain. If, after 

 further washing with water, the parasites still appeared to be 

 over-stained, either more orange-tannin or else acetone wms 

 added. The latter must be used extremely cautiously and 

 quickly rinsed off, for though at first it only extracts the blue, 

 it soon begins to take out the red from the flagellum. 

 Eventually the slide was washed with distilled water and 

 allowed to dry. 



I have since regretted that, owing to the great scarcity 



^ These proportions can be varied, of course, as is found most suitable, 

 in other cases. I may mention that I experimented some time using 

 either (1) or (2) alone in combination with (3), in various proportions, 

 but I never obtained anything like the good results that I did after 

 using both (1) and (2) together. 



