THE STRUCTURE OF TRYPANOSOMA LEWISI. 783 
and putting the slide or coverslip in it with the smear down- 
wards, no precipitate was formed on the smear. 
My recommendations for the use of this stain tor trypano- 
somes are, therefore: fix with sublimate mixtures; use the 
stain strong, 50-75 per cent.; stain for an hour, more or less ; 
and place the smear downwards in the stain. 
Twort’s stain, for “show” preparations, has the fauit that 
it stains rather faintly ; this might, perhaps, be overcome by 
letting it act longer. On the other hand it gives results 
which are extremely instructive and important (Pl. 25). he 
trypanosomes are stained in two colours, red and green. The 
two nuclei and the chromatoid granules are red; the flagellum, 
blepharoplast, and periplast are green. The general proto- 
plasm appears to have a greenish tint, perhaps due to the 
periplast. The structure of the trophonucleus and the size 
of the kinetonucleus are just as they are after iron-hema- 
toxylin. 
Other stains.—I made trial of a number of other stains, 
or combinations of stains, none of which gave results which 
could permit me to recommend their use for “show”’ pre- 
parations, but in some cases the results are interesting as 
reactions. 
Delafield’s hematoxylin.—Stock-solution made up as 
recommended in Bolles Lee’s ‘ Vade-Mecum’ (5th edition, p. 
184). For staining, a few drops added to about 30 c.c. dis- 
tilled water, acidulated with one drop of glacial acetic acid ; 
films stained in it for several hours, then washed with distilled 
water, brought up through the grades of alcohol into 90 per 
cent. ; left in this overnight, then mounted in the usual way. 
Hffects (after Hermann’s fluid) very poor; the tropho- 
nucleus a narrow dark patch with a clear space round (effect 
of fixative, see above) ; kinetonucleus indistinct ; flagellum 
faintly stained; cystoplasmic granules rather deeply stained, 
giving the body a blotchy, marbled appearance. 
I think it Inghly probable that Delafield’s heematoxylin 
would have given better results after other fixatives. I have 
recently obtained excellent results with it, on other material, 
