172 E. A. MINCHIN. 
Gribler), and then washed in a current of tap-water for a 
minute or two. After this the preparation is washed with 
distilled water, and either dried off, or passed rapidly through 
three changes of acetone into xylol, and mounted in Canada- 
balsam. 
Some preparations were also stained for me by Dr. J. D. 
‘Thomson with a mixture of azure and erythrosin in the follow- 
ing manner: A mixture was made of (1) azure I, 1 per cent., 
in equal parts of glycerine and methyl alcohol, 1 volume; (2) 
erythrosin, Ol per cent., in 0°25 per cent. formol, 2 volumes ; 
(3) distilled water, 8 volumes. The two staining fluids, kept 
ready in solution, are mixed with the water immediately 
before use, and the mixture is allowed to act for from half an 
hour to one hour; it works better if kept at about blood- 
temperature. After staining, the preparations are either 
washed with distilled water only, or also with tannin-orange 
followed by tap-water, as described above, and then either 
dried off or mounted without drying in Canada-balsam, 
passing through acetone and xylol. 
The azure-erythrosin mixture stains the trypanosomes in 
colours slightly different from that resulting from Giemsa’s 
stain. ‘I'he body is more purple in tint, and the red colour of 
the nucleus and flagellum appears rather deeper after azure- 
erythrosin. ‘he general effects of the two methods are the 
same, and do not require to be discussed separately. 
The Romanowsky stain is undoubtedly the best method for 
studying the general characters of the trypanosomes, especially 
if combined with osmic fixation, which, as I have shown, 
preserves very well the form and structure of the body and 
results in the minimum of shrinkage and deformation. I 
have always got the best results after osmic vapour followed 
by absolute alcohol; when the osmic is followed by other 
histological reagents, such as Flemming’s fluid or sublimate- 
acetic, the results are inferior, but still usually quite good, 
On the other hand I have never got good preparations with 
the Romanowsky stain after wet fixation in hardening fluids 
without previous exposure to osmic vapour; the trypanosomes 
