Rats' ""ceaseless gnawing"" is necessary to keep theft constantly growing teeth from getting too long. Rats will attack almost any defenseless animal and ""seem to know when there is a sick, helpless person"" they can gnaw to death. They eat immoderately and pollute ""many times"" what they eat. Black rats caused plague in Europe; and in North America, where there are more brown rats than there are people, we must watch out for their ""incredible power to reproduce."" These isolated bits of rat lore and gore are set down one after another without any framework or context, rather as if someone had decided to publish the Annixters' file-carded notes--selecting perhaps the more shivery items. And when generalizations are made (""Rats are among the oldest creatures on the evolutionary chain""), they are so fuzzy as to be meaningless, if not misleading. Riswold's dim, dismal pictures are quite in keeping with the rat-hole atmosphere, which seems to be intentional.