N. H. SWELLENGREBEL 
227 
Comparative observations in this respect have been carried oat by 
Minchin (1909) who studied the effect of some fixatives on wet and 
dried blood films containing Tr. lewisi, which were not in the multiplica¬ 
tion period since they presented a uniform appearance. When fixing a 
blood-drop on a cover-slip in osmic acid vapour and staining it with a 
little methyl-green (so called standard preparations) he found nuclei 
with minute karyosomes (much smaller than those figured by Moore, 
Breinl and Rosenbusch), an oval shaped blepharoplast (kinetonucleus) 
and a flagellum apparently in communication with the latter by its 
basal end; there is no space between the flagellar base and the 
blepharoplast as is 6gured in Moore and Breinl’s paper. The standard 
preparations were used as a control for the following investigation. The 
Trypanosomes of the preparations which had never been dried were 
always a little smaller than those of the standard preparations and of 
the dried films. This shows that drying has not such a marked injurious 
effect on the cells as is generally believed. The best fixatives are 
corrosive alcohol (Schaudinn) and osmic acid. Flemming’s and 
Hermann’s fluids produce shrinkage of the nucleus (which becomes 
surrounded by a bright halo) and deformation of the whole cell. The 
flagellum becomes contracted and a broad space may be seen between 
its base and the blepharoplast. 
Giemsa’s method of staining is particularly criticised. It is useful 
for demonstration but for the investigation of cytological details it is 
wholly misleading. Much better is iron-hematoxylin. Giemsa’s stain 
produces precipitates which accumulate on the chromatic granules thus 
increasing their size and forming a diffuse mass, in which no structure 
and no karyosome is to be detected. 
When considering Minchin’s results we note that it is not so much 
the dry fixation as Giemsa’s stain which gives misleading preparations 
and that statements concerning shrinkage and nuclear deformation by 
dry fixation, such as are contained in many modern textbooks ( e.g. 
Doflein 1909, Braun and Lithe 1909) lack confirmation. 
Everyone who has studied the cytology of Trypanosomes will regret 
the loss of the method of dry fixation and especially of Giemsa’s staining. 
The latter stained many a minute structure, without alcohol differentia¬ 
tion being necessary (when only care was taken to check the staining at 
the right moment). The method was consequently a progressive one, 
an advantage that the degressive Heidenhain stain does not possess. 
M. Heidenhain (1907) in his book warns against this method in the 
following words : “ Die Eisenhamatoxylinfarbungen der gewohnlichen 
