Moreover, although we are ourselves unable to detect any odorous emanation, may not our inability be due simply to the fact that our olfactory hairs are not susceptible to this particular stimulus? It may be of the same nature as odour, and yet we may be unable to perceive it, just as the moths themselves seemed anosmic to what we would call the stenches Fabre filled his room with.
These critical questions seem to me to be difficult to answer. Nevertheless, our imagination is certainly staggered by the fact of a tiny creature like a moth being able to disseminate in the immensity of atmospheric space an odour capable of perception at such great distances as a mile or a mile and a half. Hero, with the Great Peacock’s power, could have summoned Leander from a hundred miles away.
Apart, however, from such considerations for and against his opinions, one of the modern theories of odour, and of odour belonging to Fabre’s first, or material, order, is, as we shall see later on, that even it is a vibratory and not a material quality.
But leaving that development aside, and admitting for the moment the validity of Fabre’s contentions, I am bold enough to ask: Are we human beings so ignorant of the second domain of olfaction as he supposes? Is it true that we are, as he says, lacking in the equipment necessary for the exploration of that mysterious region? To answering these questions we shall presently address ourselves. In the meantime, I may forestall what I shall then say by remarking that I count it a very remarkable circumstance, if not, indeed, a significant coincidence, that, before I had become acquainted with Fabre’s writings, I had, considering the phenomena of human olfaction and psychology alone, actually asked myself the same question as he asks, and had come to very much the same conclusion.
CHAPTER III
OLFACTORY MEMORY
The predominant special senses in man are vision and hearing, olfaction occupying a quite unimportant position in the scale.
Smell and taste, by the way, are usually regarded not only as allied senses, but also as if they were akin in their nature and function. Allied they are, undoubtedly, seeing that both subserve the function of food-perception. But the resemblance ends there. For, of the two, smell is at once the more delicate and the more extensive in capacity, and, as they differ widely in their anatomical structure, there can be no doubt but that in physiological action also they are dissimilar.
The taste-bulbs are capable of appreciating four sensations only, and these quite simple, while the capacity of the olfactory organ, as we shall see more fully later on, is practically unlimited. All the subtlety of “taste,” all that we call “flavour,” is an olfactory sensation. Thus, people devoid of the sense of smell cannot discern the finer savours. They would be unable to distinguish, say, a vanilla from a strawberry ice. All they could tell would be that both were cold and sweet.
The popular phrase which refers the appreciation of the finer shades of taste to the “palate” we may therefore look upon as an attempt to express the feeling that delicate flavours are sensed somewhere higher up than in the mouth. So that a “man of taste” is really a man of smell, and all the literary eloquence in praise of wine and dainty food, to say nothing of the more prosy cookery books, is, in reality, a general hymn of adulation offered unwittingly to the nose!
Compared with sight and hearing, however, smell in man is only one of the minor senses. But, as if to make up for a position so inferior, it is remarkable as being the most subtle of all our senses, possibly, as some hold, because of the ancestral appeal to our (more or less repressed) animal nature. So subtle is it, indeed, that I am persuaded its stimuli may not, on occasion, emerge into consciousness at all. They remain below the threshold. So that, although subjected to their influence, we may remain ignorant of the cause of that influence. For smell often operates powerfully, not only in surreptitiously enriching and invigorating the mental impression of an event, but also in directing at times the flow of ideas into some particular channel independent of the will. The influence of the perfume of a woman’s hair in unexpectedly arousing a feeling of intimacy will appeal to the male reader as a good example of this upsurging interference with the placid flow of normal ideation.