A STUDY OF THE MECHANISM OF ABSORPTION OF SUBSTANCES FROM THE NASOPHARYNX

Two previous communications have indicated that the nasopharynx constitutes an area of peculiar physiologic significance. Observations on several cases of diabetes insipidus¹ uniformly showed that although the watery extract of the pituitary gland was not absorbed from any other internal or external surface of the body, it nevertheless gained rapid and effective entrance through the nasopharynx. The disclosure of such an interesting physiologic mechanism raised the query whether this absorptive power might extend also to particulate matter. Using the proper precautions to prevent absorption by any other route, it was found that particulate matter in the form of pulverized lead carbonate was readily absorbed from the upper air passage of cats and dogs.² The absorption was rapid and greatly in excess of the minimal toxic dose. Although these facts demonstrated that both solutions and particulate matter might eventually traverse the normal nasopharyngeal mucous membrane with readiness, they gave no clue