THE FERTILIZABLE PERIOD OF THE EGGS OF FUNDULUS HETEROCLITUS AND SOME ASSOCIATED PHENOMENA

Abstract

The fertilizable period of the ave. egg in sea water is 15-20 min. The manner of entrance of the sperm into the egg is described. Insemination which is delayed for 20 or more min. not only reduces the % of fertilization but also increases the % of abnormalities and decreases the % of hatched eggs in those lots of eggs which are fertilized. Sea water initiates development in the unfertilized eggs through the blastodisc stage, including the disappearance of platelets and formation of the peri-vitelline space. However, the % of eggs which develop these stages is higher in the fertilized than in the unfertilized eggs. Also, the stages occur sooner and are of shorter duration in the fertilized eggs. The platelets are directly concerned in the formation of the blastodisc. The perivitelline space appears to be formed principally by a change in the permeability of the egg cortex. As the yolk shrinks, it leaves the vitelline membrane to retain the original shape and size of the egg.