Species differences in taste responses.

ANY electrophysiological experiments M have been made in order to determine the properties of the chemoreceptors of the tongue of the rat (I). Comparison of some of the results with those attained by investigators using other techniques revealed differences in the response to a series of inorganic salts among animals belonging to various phylogenetic orders. For example, the behavioral data obtained with human subjects does not correlate directly with the electrophysiological data obtained on rats. Such differences could be explained in either of two ways. First, the behavioral data represents a complex response of the over-all animal to the stimulation of the tongue. This involves many complex processes other than those present in the response of a particular group of chemoreceptors as recorded electrophysiologically. Second, actual differences in the response of the chemoreceptors on the tongue may be present from one species of animals to another. The latter possibility was previously suggested as a consequence of a theoretical treatment of the mechanisms involved in the stimulation of taste receptors by salts (2). It has been found that the ions are very weakly bound to the receptors. Therefore, the binding of various salts should be dependent upon the over-all configurations of the receptor molecules, the available side chains, the proximity of neighboring molecules, etc. It is to be expected that these differences should be accentuated from one species to another. It is the purpose of this paper to show that differences in respon stimu lus do occur from one .se to species a chemical to another.