While other fixing agents were used, Flemming’s chromo-acetic-osmic
mixture (strong) proved the best. Its fixation was satisfactory in
all but a few stages, where the chemical changes going on in the cell
are such that it seems difficult, probably impossible, to secure
good, clear results; at least, neither Gilson’s nor Zenker’s mixture
did any better on cells in these stages.
Heidenhain’s iron-hæmatoxylin stain gave the best results, although
Flemming’s three-color method was very satisfactory.
Most of the observations are made from sectioned material, but smear
preparations were used for advanced spermatozoa.