H. Seidelin 
101 
even for a short time they lose in staining power. From the staining 
solution the preparations are passed to tap water, not to distilled water, 
and then into pure acetone, or this licpiid is continually dropped on the 
slide until the desired differentiation is obtained. When the prepara¬ 
tions have been strongly over-stained the decolouration may take a long 
time, very often half an hour or more, and then one seems to get the 
best results. The progress of the differentiation should be frecpiently 
controlled under the microscope. From pure acetone, which I prefer to 
the first mixture of Giemsa of 95 acetone and 5 xylol, the section passes 
into the second mixture of 70 acetone and 30 xylol, and after 5 minutes 
into a third mixture of 30 acetone and 70 xylol. It is decidedly better 
to use these three steps, instead of only two as Giemsa recommended. 
It sometimes happens, however, that the last named mixture of acetone 
and xylol becomes cloudy, but it seems to keep clear when both the 
xylol and the acetone are very pure; if it becomes cloudy at least equal 
parts of the two substances may be used. It is certainly not convenient 
to pass the specimens directly from 70 acetone and 30 xylol into pure 
xylol. After five minutes in each of the two mixtures pass into pure 
xylol, which should be changed once so that no trace of acetone may be 
left. The sections may be mounted in Canada-balsam, but I have for 
some time been using Damarlack, in which they should keep much 
longer without fading, if we can draw any conclusions from experience 
with other stains, which would seem to last much longer in Damarlack, 
as I have learned from Prof. C. J. Salomonsen in Copenhagen. 
Results. This method has been tried during the last few months 
on the same material as the iron-haematein stain and at an earlier date 
on a good deal more. The different elements stain in the same way as 
by the ordinary Giemsa method and the results have been uniformly 
good on material which had been fixed in sublimate-alcohol, whilst 
after formalin and osmic acid they have been as constantly negative. 
If there is any difference, the chromatin stains still better than in dry 
preparations, and I can quite confirm Giemsa’s assertion, that in blood 
smears and other films better results can be obtained after wet fixation 
than by the dry method. 
It may be convenient to give a brief summary of this technique 
also, though the differences from the one given in Giemsa’s paper are 
very small: 
1. Fixation, hardening, and embedding as above. 
2. Sections of a uniform thickness of 5 /a, or less. 
3. Xylol, alcohols of diminishing strengths, tap water. 
7—2 
