  Mathew-Fenn et al. (Science (2008) 322, 446-9) measured end-to-end distances
of short DNA and concluded that stretching fluctuations in several consecutive
turns of the double helix should be strongly correlated. I argue that this
conclusion is based on incorrect assumptions, notably, on a simplistic
treatment of the excluded volume effect of reporter labels. Contrary to the
author's claim, their conclusion is not supported by other data.
