1002
Noture and schema
aspect
ot fixation
Histologic aspect
Cephatic
region
Trunk
region
Totat
X-irradiation
Control
of operation
Mocroscopic
animal pole
Irradiation of
@,O|O
(LL
protective
Irradiation of
vegetative pole
screen
4
aes
Rnnceaernn
racaracacsrerereecereete
et
SENSEREE
eee ee eerereTE
see
68888833888
% OF STRUCTURES INDUCED
Fig. 1—Result of irradiation with 1170 R on the young Pleurodcle gastruia.
T2
NORMAL
1170 R
30,000 R
150,000 R
Fig. 2— Percentage of structure induced in a fragment of ectoderm by a dorsal
blastoporal lip, either normal or X-rayed.