| Comments |
P.128 bottom paragraph: "Fertilization and nuclear DNA content-Interspecific variation has been noted in the duration of the period between penetration into the embryo sac by the male gametes and their fusion with the female nuclei (primary sources Vassileva-Dryanovska 1966a,b). Although data for the duration of this period are available for only a few species, it seems that a simple relation exists between its minimum duration and the DNA content of the nuclei involved. Thus, the five species in which fusion occurs immediately after penetration all have a 3C nuclear DNA content of 12 pg or less: Tradescantia paludosa, in which fusion does not occur until about 24 h after penetration, has 54 pg: and the species in which fusion does not occur until several days after penetration have nuclear DNA contents in excess of 100 pg (table 8). In species with high nuclear DNA contents the sperm nuclei remain adpressed to the female nuclei for several days while they change their structure and increase their volumes to match that of the female nuclei before fusion occurs. This behavior may be related to the condensation of the male nuclei before they pass along the pollen tube." See note beneath table |