416
CH. DEVILLERS
1 mm
FIG. 19. Experiments on the co-ordination of the epibolic forces in the egg of Salmo
irideus (from Devillers, 1952). Left column: evolution of the (young) control; central
column: combination of an old germ GA (coming from a gastrula of the right column)
and a young yolk VJ; right column: combination of a young germ GJ (coming from the
central column) and an old yolk. In this combination epiboly only starts again after 24
hours at the same time as in controls. Note the difference of development between the
normal embryo (left) and that of the composite germ at the same moment (96 hrs).
Eggs treated before epiboly \ show an unexplained phenomenon
of 'catching up' or of acceleration of epiboly (Devillers, 1950a). For
supposed that at the same time the epibolic forces (enveloping layer and
syncytium) are stopped and that the traction exerted by the ridge
cannot stretch the germ.
CH. DEVILLERS
1 mm
FIG. 19. Experiments on the co-ordination of the epibolic forces in the egg of Salmo
irideus (from Devillers, 1952). Left column: evolution of the (young) control; central
column: combination of an old germ GA (coming from a gastrula of the right column)
and a young yolk VJ; right column: combination of a young germ GJ (coming from the
central column) and an old yolk. In this combination epiboly only starts again after 24
hours at the same time as in controls. Note the difference of development between the
normal embryo (left) and that of the composite germ at the same moment (96 hrs).
Eggs treated before epiboly \ show an unexplained phenomenon
of 'catching up' or of acceleration of epiboly (Devillers, 1950a). For
supposed that at the same time the epibolic forces (enveloping layer and
syncytium) are stopped and that the traction exerted by the ridge
cannot stretch the germ.