either one or the other according to their relation to life. Where sense serves not life but itself, as with the epicure, a new order of pleasures and pains is determined which is not within our present scope of discussion. This variability of pleasure-pain tone of sensations even under natural evolution shows that the main force at least of their pleasurability or the contrary does not lie in the affection of the sense organ itself. If a given sensation, for example, bitterness, were painful in all degrees only because of its harmfulness to the sense organ, how could this variability be explained? We consider that the tasting bitterness, for example, arose through painful stomachic and bowel experience with herbs which had this quality, and which by sensing efforts were so cognized at length, and pain connected by its very origin with sense of bitterness, which becomes in all degrees painful. The identifying the nutritiously harmful weed by tasting its bitterness has the pain quality of its effects, since the tasting has grown up in connection with its effects. It is out of actual injurious and painful experiences that the organism is led to put out sensing effort and to reach such a sensation as that of a bitter taste whose pain value is mainly, at least, due to the actual results of the substance lower down in the alimentary canal. A sense of bitterness becomes disagreeable in all degrees, for in its inception, when first sensed, it has its connection with the pain effects which stimulate this sensing. To discriminate the unnutritious or poisonous by tasting is a grand achievement, securing the rejection at the very opening, the mouth of the alimentary canal, in place of rejection by nausea from the stomach itself. The organism which could only know that a certain substance was bad for it by very painful nausea, now knows its badness by the comparatively painless tasting bad. Whatever tastes bad, is bad.