FLAGELLAR MOTILITY IS NOT INVOLVED IN THE INCORPORATION OF THE SPERM INTO THE EGG AT FERTILIZATION*

Abstract
Cinemicrography of sea urchin fertilization reveals that the fertilizing sperm is one of the first sperm to attach to the egg. Just before the cortical reaction the fertilizing sperm ceases motility and is incorporated into the egg without flagellar beating. The rate of incorporation is 5-11 .mu.m/s and is constant. Lytechinus pictus sperm rendered immotile by azide treatment can bind to and fertilize eggs but binding, and hence fertilization, is blocked by azide treatment of Strongylocentrotus purpuratus gametes.