E.E. Just. Image courtesy of
????, Univ. of Pennsylvania.
The basic sequence of events of
the slow block to polypsermy has been known for decades.
One of the first careful studies of the dynamics of this
process was carried by the African-American developmental
biologist E. E. Just. Below is a
reproduction of hand-drawn pictures of the process of
fertilization envelope elevation drawn by Just (original digitization courtesy of
Scott Gilbert, Swarthmore College).
Below: Hand-drawn pictures of
the process of fertilization envelope elevation drawn by
E.E. Just. The arrow and asterisk in frame 2 shows the site
of sperm entry. The asterisks (hard to see) in subsequent
frames show the same sight at later times.
