Our knowledge of the sense of taste among the lower (invertebrate) animals is imperfect, and is largely based rather on observation of their habits than on the evidence of anatomical structure. Here, again, comes in the difficulty of distinguishing between taste and smell. But even if the caterpillars which refuse to eat all but one or two special herbs, or the races of bloodsuckers which seem to have individual and special tastes, are guided in part by an olfactory sense, there is much evidence which seems to admit of no alternative explanation. Moisten, for example, the antennæ of a cockroach with a solution of Epsom salts or quinine, and watch him suck it off; or repeat F. Will's experiments on bees, tempting them with sugar, and then perfidiously substituting pounded alum. The way in which these little insects splutter and spit suggests that, whatever may be the psychological effect, the physiological effect is analogous to that produced in us by an exceedingly nasty taste. Here smell would seem to be excluded. Forel, moreover, mixed strychnine with honey, and offered it to his ants. The smell of the honey attracted them, but when they began to feed, the effect of the taste was at once evident. The organs of taste in insects are probably certain minute pits, in each of which is a delicate taste-hair, which, in some cases, is perforated at the free end. They occur in the maxillæ and tongue in ants and bees, and on the proboscis of the fly. In many of the invertebrates, the crayfish and the earthworm, for example--to take two instances from very different groups--observation seems to show that a sense of taste is developed, for they have marked and decided food-preferences. Nevertheless, the existence of special organs for this purpose has not been definitely proved. The sense of taste no doubt ministers to the enjoyment of life. But, presumably, it has been developed in subservience to the process of nutrition. Primarily, taste was not an end in itself, but was to guide the organism in its selection of food that could be assimilated. Nice and nasty were at first, and still are to a large extent, synonymous with good-for-eating and not-good-for-eating. With unwonted substances, however, its testimony may be false. Sugar of lead is sweet, but fatal. Brought to a new country, cattle often eat, apparently with relish, poisonous plants. Still, under normal circumstances, the testimony of taste is reliable. * * * * *