The immediate dispersal of a fluid delivered to anaesthetized mice by the intranasal and intra-oral techniques has been studied by means of a radio-active tracer method. The results clearly show that the intra-orally inoculated animal accepts a larger proportion of the total volume inoculated and that a significantly higher fraction of this reaches the lungs than in mice inoculated by the intra-nasal technique.

The authors would like to thank Dr I. Friedmann and Dr H. A. B. Simons for having made this work possible; also, Mr D. Arnott for a generous gift of labelled di-iodofluorescein, and Dr D. A. Osborn and Dr K. Weinbren for helpful suggestions.