When a basidiospore matures, sugars present in the cell wall begin to serve as condensation loci for water vapour in the air. Two separate regions of condensation are critical. At the pointed tip of the spore (the hilum) closest to the supporting basidium, Buller's drop builds up as a large, almost spherical water droplet.
when a basidiospore matures sugars present in the cell wall begin to serve as condensation loci for water vapour in the air two separate regions of condensation are critical at the pointed tip of the spore (the hilum) closest to the supporting basidium buller's drop builds up as a large almost spherical water droplet