Division of the Generative Nucleus in the Pollen Tube of Lilium

1. The gametophytic development, after the formation of the mature spore, is described for Lilium regale. 2. Explanations for the peculiar configurations of generative cell chromosomes are presented. 3. Evidence is presented that the chromosome is more of an autosome unit at mitosis than has previously been assumed. 4. A cytological explanation of the mechanism of the formation of chromosome interchanges is presented.