THE COMMON COLD

The nose contains three different types of epithelium; (1) the squamous epithelium in the vestibule, (2) the respiratory epithelium and (3) the special sense epithelium. The squamous epithelium of the vestibule is simply a portion of the skin that extends within the nostril. It does not enter into the present study. The respiratory epithelium takes in the largest portion of the nose. It extends from the squamous epithelium anteriorly to the squamous epithelium of the nasopharynx posteriorly and from the floor of the nose up to the olfactory area. The respiratory epithelium is pseudo-stratified, ciliated columnar in type (figs. 1 and 2). The superficial layer is composed of long columnar cells, each of which is surmounted by a tuft of rather long cilia. It contains many goblet cells. There are usually from three to five layers of these. All of the epithelial cells, including the surface columnar cells, extend