Abstract
Living mature pollen contains two or more times riboflavin than in other parts of plant. In germinative pollen the riboflavin contained is always of ester form, being mostly FMN, in less degree FAD, but no free form. When pollen has lost germinating power, the decomposition of FAD is seen to take place with considerable rapidity, and diminishing of FMN is observed, both presumably undergoing a change from ester form to free one.
