  E. M. Chudnovsky has recently posted on the ArXive his Reply
(arXiv:0805.2918) to my Comment (Phys. Rev. Lett. 100, 199703 (2008)) on his
recent Letter (E. M. Chudnovsky, Phys. Rev. Lett. 99, 206601 (2007)). In order
to avoid possible misunderstandings in the evaluation of his Letter, I am
posting my Comment with some remarks on the contents of his Reply.
