Finally, the taste mechanism is extremely simple when compared with the so-called higher senses, especially that portion of it whose function is to prepare the stimuli to act upon the receiving mechanism. The taste organ is generally believed to represent a stage in evolution very near to the original structures from which all of the sense organs have developed. That is, looked at from the evolutionary point of view, it is a more primitive and less highly developed mechanism. _The Salivary Glands and Their Activity_ Consider first those portions of the taste organ which perform the mechanical function of preparing the stimulus to act upon the receiving mechanism or the sensory ends of taste. Most important of these are the salivary glands and the tongue. The latter through its movements facilitates contact of the taste substances with the sensory ends of taste, and the former secrete saliva, which dissolves the sapid substances, reducing them to the liquid form necessary for arousing taste sensations. The salivary glands and their secretions are of interest to the student of taste only in so far as their activity forms a necessary step in the taste process. In this connection it must be remembered that the chief function of the saliva is the part it plays in the process of digestion. As suggested above, the function of the saliva in the taste process is merely that of dissolving or transforming solids into liquid form. Consequently, the chemical constitution of the saliva and the detailed structure of the glands are aside from our interest. The action of these glands, three in number, and called the parotid, the submaxillary, and the sublingual, is of the reflex type. The stimuli for the reflex are numerous, and, it appears, are not the same for all of the glands. For instance, the submaxillary glands are said to secrete upon the presence of certain foods, acids in the mouth, the chewing of meats, etc. On the other hand, the stimulus for the parotid gland has been shown by Pavlow to be the presence of dry substances in the mouth. If no distinction is made between glands, it may be said that watery foods cause only a slight flow of saliva, while dry foods cause a large flow of saliva. One sees, then, a set of reflexes which not only promote the digestion of foods, but which also tend to make them tastable. These two functions are not entirely separate ones, for it has been shown by experiment that the tastes of various foods are determining factors in causing and regulating the flow of gastric juice in the stomach.