780 E. A. MINCHIN. 
pipe immersed below the surface of the water; the cover- 
slip will neither sink nor run over the edge of the beaker 
with the current, and can be washed with safety for any 
length of time. After the tap-water I put them for a few 
minutes in distilled water, then pass them up through the 
grades of alcohol into absolute, in which I leave them for 
at least an hour, then pass them through xylol into Canada- 
balsam. 
Asa rule I have always done several films at the same time, 
and extract the stain to different degrees in different films 
(compare figs. 25-28, 29-32). When the trypanosomes come 
out of the hematoxylin they appear uniformly black all 
through. ‘The stain first comes out of the general cytoplasm ; 
next out of the cytoplasmic granules and the body of the 
nucleus, leaving the karyosome sharp; with more extraction 
it is taken out of the flagellum and blepharoplast; the bodies 
that retain it the longest are the kinetonucleus and karyo- 
some, especially the former. In fish-trypanosomes I was able, 
in some instances, to see myonemes after moderate extraction 
when the stain was only removed from the general cytoplasm ; 
but in Trypanosoma lewisi I have never succeeded in seeing 
myonemes. 
Iron-hematoxylin is the stain of choice for minute struc- 
tural details of the nuclei and Jocomotor apparatus. Perfect 
reliance can, in my opinion, be placed on the results yielded 
by it, and the stain can always be trusted to give uniform 
results with the same degree of extraction. It stains most 
sharply and clearly after sublimate mixtures, less so after 
osmic vapour and alcohol simply. I have never had good 
results with it in films dried at any time, before or after fixa- 
tion. I have also never found any advantage, so far as 
trypanosomes are concerned, in counter-staining with eosin, 
orange, etc. ; all such processes appear to me simply a waste 
of time. 
(3) Twort’s stain.—This is a combination of neutral red 
and Licht-griin invented by Dr. Twort, of the Bacteriological 
Laboratory, London Hospital Medical College, who has 
