120
HERMAN
DENIS
Early cleavage
Late cleavage
10
20
30
0
(e)
Tube no.
(f)
FIG. 2. Sucrose density gradient of the RNA extracted from 150 embryos of
various stages. The embryos were labeled by injecting
3 2
P into the female. All the
nucleic acids synthesized from fertilization until the indicated stages are thus
labeled. Open circles—optical density; filled circles—radioactivity.