tmpar <- par( mar=c(3.1,3.1,.1,.1), mfrow=c(1,2) )

mqqnorm( cloning$titer, group=cloning$code, xlab="", ylab="" )
mtext( "(a) raw data", 1, 2 )
mtext( "quantiles", 2, 2 )

mqqnorm( resid( cloning.fit ), group=cloning$code, xlab="", ylab="" )
mtext( "(b) residuals", 1, 2 )

par( tmpar )