H. Seidelin 
95 
transparent it is necessary to differentiate so much, that the nuclei are 
also decolourized. A certain inconvenience is also experienced because 
of the long duration of the staining process, at least 30 hours when the 
original Heidenhain’s method (1896) is adhered to; and although the 
more recent modifications, especially that of Rosenbusch (1908), have 
to a great extent overcome this difficulty, they still suffer from the two 
other disadvantages referred to. 
I have therefore endeavoured to develop a quick and reliable stain 
of a similar nature, which does not require a differentiation. Beginning 
with the fact that haematein, as a rule, stains less diffusely than 
haematoxylin, I tried systematically mixtures of alcoholic haematein 
solutions and watery solutions of lithium carbonate, and obtained an 
excellent colouration of the tissue-nuclei, but did not find it satisfactory 
for Protozoa. The following formula gave the best results, staining 
5 minutes: 
Haematein sol. (1 “/o in 96 ”/o a-lc.) ... ... 1 c.c. 
Distilled water ... ... ... ... ... 4 c.c. 
Saturated aqueous solution of lithium carbonate 5 drops. 
Afterwards different combinations of iron-alum and haematein were 
tried, but always gave diffuse stains, so that a differentiation could not 
be dispensed with. Then I proceeded to experiment with alcoholic 
haematein and watery iron-perchloride solutions, after the manner of 
Weigert’s iron-haematoxylin method (1904), which is known as an 
excellent nuclear stain for histological purposes, but as a rule does not 
stain Protozoa well. The following combinations were tried, A being a 
1 per cent, solution of haematein and B the iron-perchloride solution of 
Weigert: 
4 A -t- 1 B diffuse stain 
3 A -f 2 B good, both for sections and films 
2^ A -1- 2^ B good for sections, but too weak for films 
2 A -f 3 B faint 
1 A -I- 4 B very faint. 
I shall now describe the necessary details concerning the process. 
It is evidently only a slight modification of Weigert’s method, but I 
believe that the difference will be found to make the present method 
useful in a certain number of cases, where Weigert’s cannot be used. 
Fixation. Sublimate-mixtures give the best results. I prefer 
Schaudinn’s liquid : two parts of a saturated aqueous solution of mercury 
