1900] LIFE HISTORY OF QUERCUS 409 
development in which the several structures pass the winter, and 
the sequence of their development as it occurs in the spring. 
Beginning with May 5 and continuing to July 7, gatherings 
were made at intervals of two or three days, and in order that 
the material might be typical it was mostly taken from the upper 
branches of a single thrifty tree. : 
Owing to the protective covering of scales and glandular 
hairs which prevented the penetration of fixing and imbedding 
agents, great care was exercised in removing this so as to expose 
freely the structures to be investigated. Several fixing agents 
were tried, but chromo-acetic and picro-acetic were most satis- 
factory. The chromic agent preserved the material well, but 
rendered it more brittle and difficult to section. The picric agent 
is to be preferred. The chromo-acetic was a I per cent. aqueous 
solution of chromic acid with 4 per cent. acetic acid. The picro- 
acetic was a saturated solution of picric acid in 70 per cent. alco- 
hol with 0.5 per cent. acetic acid. The chromic fluid proved 
best when the material was wet in 95 per cent. alcohol, and 
quickly passed into the fixing agent. ‘The picric was most satis- 
factory when used at a temperature of 80 to 90 degrees Centi- 
grade. 
Thus fixed, the material was dehydrated with successive 
grades of alcohol, passed into xylol, imbedded in paraffin, cut in 
serial sections 5 and 10» in thickness, and stained upon the slide. 
Several stains were tried. Cyanin and erythrosin proved good 
for early stages, Delafield’s haematoxylin for archesporial stage, 
and fuchsin and iodine green for embryo-sac and embryo. 
THE STAMENS AND POLLEN. 
Material collected in early spring (March 7) may be taken 
as fairly representing the stage of development in which the 
microsporophylls pass the winter. While the structure is well 
differentiated into filament and anther, the latter consists of a 
mass of apparently uniform cells ( figs. 7, 2). Upon the approach 
curs a rapid development and 
of a growing temperature there oc 
he usual regions of 
a corresponding early differentiation into t 
