For the fixation of material used in these studies, it has been found
that the osmic acid mixtures of Flemming and Hermann are the most
generally applicable and are productive of the best results. In
connection with these, however, Gilson’s acetonitric-sublimate mixture
has been tried, and frequently affords an excellent fixation. Extensive
shrinkage in the melted paraffin is sure to follow the use of sublimate
mixtures unless celloidin is used to support the soft tissue. This
double infiltration of celloidin, followed by paraffin, has been found
the best method of securing clear and accurate figures, for, because of
the lessened shrinkage, the elements are not crowded together and
rendered indistinct. This circumstance is particularly fortunate in the
case of the Locustid cells, where the nuclear elements are so numerous
and crowded.
The stains employed are the iron-hæmatoxylin of Heidenhain and the
safranin-gentian violet-orange combination of Flemming. For general
purposes, nothing excels the hæmatoxylin stain, but it is frequently
advantageous to trace the chemical changes undergone by the different
cell elements in the process of mitosis, and the aniline stain above
mentioned serves excellently for this. Kernschwarz has also been found a
valuable stain for some purposes.