It was for this reason that I proposed to myself the task of collecting fresh documents, and of inquiring whether there are not great differences between one individual and another as regards the memory of impressions. This would explain the want of harmony among authorities on this point. Having eliminated all vague and doubtful answers, and those which are not to the point, I have collected about sixty _dossiers_. Each person (all being adults, of both sexes, and various stages of culture) was directly questioned by myself, and the answers immediately noted. Besides these, I have received several long written communications, which I reckon among my best material. The nature of the questions asked will be sufficiently evident from the following summary, which contains the principal results of my inquiry. I shall confine myself to a bare statement of the facts; the interpretation will come later. 1. _Images of taste and smell._—I was disposed to admit that they are not subject to any spontaneous revivability, and still less to a voluntary one, being, for my own part, quite incapable of recalling a single one, even in the faintest degree. The answers have put me completely in the wrong—the negatives being 40 per cent., the positives 60 per cent. More accurately, 40 per cent. persons revive no image, 48 per cent. revive some, 12 per cent. declare themselves capable of reviving all, or nearly all, at pleasure. The majority of cases, therefore, allows of the spontaneous revival of some odours only. Those most frequently mentioned are pinks, musk, violets, heliotrope, carbolic acid, the smell of the country, of grass, etc. The conditions under which the image appears are various. For some persons this is unaccompanied by any visual, tactile, or other representation. With the majority, the imaginary odour ultimately excites the corresponding visual image (that of a flower, a bottle of scent, etc.). Many have first to evoke the visual image, and, in time, succeed in exciting the olfactory one. Two individuals affirm that, on reading the description of a landscape, they immediately perceive the characteristic odours. Here the sign is sufficient. One of them, a novelist, is sometimes conscious of thirst under the same conditions. In the two following cases the “olfactory image” only exists in a single instance, and appears to be produced by the combined operation of concomitant circumstances.