H, Seidelin 
97 
are in use in Prof. Minchin’s laboratory some very convenient glass- 
dishes of the exact size of a slide, so that a comparatively small quantity 
of the staining solution is necessary. A longer time than five minutes 
is only very rarely necessary, but the staining may be controlled at any 
moment by examining the preparation with a low power after washing, 
and the slide may then, if necessary, be returned to the mixture. For 
showing the structure of certain nuclei, for instance of lymphocytes, an 
even shorter time in rare cases may be preferable. The sections are 
washed in tap water for several minutes; a longer washing, even of 
several hours, does not harm them, and may sometimes be useful in 
making the colour blacker, if it is too blue. They ai’e subsequently 
taken through alcohols of increasing strengths to absolute and then 
xylol, and are mounted in Canada-balsam, or Damarlack. 
Results. The stain has been tried on the different materials 
containing Protozoa, which have been available at the present time, 
especially on smears of rat-blood containing Trypanosoma leiuisi, also 
on the contents of the digestive tube of leeches containing trypanosomes 
from fresh-water fishes; most of the latter forms were very small, and 
many of them extremely slender and very difficult to stain by any 
method. The stain was further applied to many sections, e.g. of leeches 
containing the above mentioned trypanosomes, and of human spleen 
infected with Leishmania donovani ; also some sections without Protozoa 
were treated with the stain in order to try its value as an ordinary 
histological method. The tests, to which the methods have been 
subjected, have therefore been varied, if not very numerous, and several 
of them have been ratber severe. As a rule it may be said that the 
stain has given the same results as the iron-haematoxylin method, but 
in much less time. In some cases it has proved distinctly superior, 
especially in some of the sections of leeches, which contained compact 
masses of half digested blood; an excellent result was obtained by the 
present method, whilst the preparations stained after Heidenhain or 
Rosenbusch were quite useless, as either the whole mass presented a 
nearly uniform black colour, or else, when the decolouration was carried 
far enough to make out details, the trypanosome nuclei were decolourized 
also. 
The karyosome and chromatiir-structures stain black, the kineto- 
nucleus being especially dark; the flagellum is grey and shows very 
sharply whilst the protoplasm takes a pale grey colour. As mentioned 
above, instead of the proportion of 3 to 2, equal parts of the two 
solutions may be used in sections when a particularly strong contrast 
