ABSTRACT
INTRODUCTION Across species, the common function of the nasal cavities is the detection of chemical stimuli. In tetrapod vertebrates, the nasal cavities assumed another function-serving as the first part of the respiratory passages. In this capacity, they also serve to humidify, warm, and filter inspired air. This aspect of the nasal cavities is discussed in chapters 1 and 2. In fact, some animals, such as mice, rats, and the human newborn, are obligate nose breathers (i.e., can only breathe through their noses). In some mammals, this respiratory function may overshadow the detection of chemicals.
