“…Microscopic examina tion of the pollen showed it to contain plant hairs, plant and insect fragments and a few grains of grass pollen but much less than 0.1 % contamination with extraneous material (15). This extract was prepared as previously described (5) and stored in the lyophylized state, under vacuum, at 2-5 "Cl. Potency tested against the reference extract, 382, showed 508 to contain 480000 units per ml (Table I and Fig.…”