The effect of doxorubicin and phenytoin on Paracentrotus lividus devel
opment and fertilization is reported. Doxorubicin at concentrations be
tween 1.4 and 1.8 mu M causes severe disturbances of development and a
t 2.0 mu M, complete embryonic degeneration, if added in the period fr
om fertilization on. Concentrations up to 20 mu M are ineffective on d
evelopment if the treatment is started at 12 h after fertilization. Ph
enytoin at concentrations between 4.0 and 7.0 mu M causes severe distu
rbances of development, if added from 5 min after fertilization on. Co
ncentrations of 10 mu M are lethal to all embryos. Again, if the drug
is added at 12 h after fertilization, no effect is observed up to the
concentration of 20 mu M. Both drugs are ineffective on the fertilizat
ion process up to the concentration of 20 mu M for doxorubicin and of
200 mu M for phenytoin.