SPERMATOPHYTES—GYMNOSPERMS 
281 
Spermatogenesis. —In October the clusters of staminate cones 
which are to shed their pollen in the coming spring are already quite 
conspicuous. The cones should be picked off separately, and the 
Fig. 98 .—Pinus Strobus: photomicrograph of longitudinal radial section of mature wood of 
stem, showing bordered pits and bars of Sanio. Safranin and crystal-violet, Eastman Commercial 
Ortho film, Wratten B filter (green); Spencer 4-mm. objective, N.A. .65; arc light; exposure, £ 
second. Negative by Dr. P. J. Sedgwick. X166. 
