184 BOTANICAL GAZETTE [SEPTEMBER 
KILLING AGENTS.— Flemming’s weaker fluid, Hermann’s 
chromacetic acid, and bichromate of potassium combined with 
acetic acid, gave the best results. Corrosive sublimate, absolute 
alcohol, picric acid, Merkel’s and Perenyi’s fluid were tried, but 
the results were unsatisfactory in that I failed to get such suc- 
cessful staining after their use. 
These fixing fluids were used boiling hot. In the case of 
the Flemming, the chromic acid and water were brought to the 
boiling point, the osmic and acetic acids quickly added and the 
mixture poured over the strobili which had previously been 
removed from the plants. The vessel was covered tightly and 
the contents allowed to cool gradually to a temperature of 
30° C. The spores were fixed in twenty four hours, but often 
were left in the killing fluid two or three days with no deleteri- 
ous effects. Water of approximately the same temperature 
(30° C.) was used for washing, in very large quantities, and 
changed frequently for two days. Sometimes it was more con- 
venient to use cold running water, in which case three days’ 
washing was necessary to remove all acid. The dehydrating 
process was equally gradual: twelve hours each in Io per cent., 
20 per cent., 30 per cent., 50 per cent., 75 per cent., and 80 per 
cent. alcohol respectively. In g5 and 100 per cent. three days 
each, and the alcohol changed each day. Xylol was added to 
the specimens with even more caution, as an examination of 
material from day to day during these manipulations disclosed 
the fact that at this point danger of collapse was greatest. Six 
intermediate grades between absolute alcohol and pure xylol were 
employed, each for twenty-four hours. The strobili remained 
in pure xylol until they became transparent, which frequently 
was not for a week, dependent upon the age of the spores. 
When this condition was obtained, the xylol was replaced 
by fresh, and small bits of soft paraffin (melting point 30° C.) 
were added gradually as long as they would dissolve at the 
temperature of the room. This usually required two days. 
Thence the vessel was removed to the bath (temperature 40° 
C.), which was raised slowly to 54° C., soft paraffin being added 
