PARTY ON CAGING AND PENNING Edited for the Working Party by:

The Working Party considered that the caging of mice and rats was the most urgent of the problems before them, affecting a large number of breeders and users, as well as cage manufacturers. We requested information from 78 principal laboratories in Great Britain concerned with the breeding and use of mice and rats. Unfortunately the 44 replies were so varied that no con-sensus, or even trend, of opinion could be discerned from the information received. As a result, the working party, with guidance from a cage manu-facturer, decided upon the recommendations contained in this report. A survey of the literature similarly revealed a complete lack of uniformity in design, dimensions and materials used for any particular caging purpose. Furthermore, there were no reports of critical investigations of area require