The Journal welcomes comments from its readers. All communications should be addressed to the Editor and bear the full name and address of the writer. A selection of those received will be published periodically in these columns. When a comment is received regarding an article or review published in the Journal, and we feel it merits serious consideration, the author will be given the option to respond in kind. As a matter of policy, such exchanges are normally limited to one round. The Journal reserves the right to edit or abridge all contributions. In addition to letters of comment, communications on other information of interest will be printed as space is available.