Let us commence with a few of the details, mostly unimportant, upon which there is general agreement.
Consider, first of all, the variety, the almost infinite variety, of odours. We have, for example, all the odours of the world of Nature, the emanations of inorganic matter, of the earth itself, its soil and its minerals ; to these we must add the multitudinous perfumes of the vegetable kingdom, of barks, roots, leaves, flowers and fruits, including those of growing herbaceous plants, which differ so widely from one another that it is said of Rousseau, whose myopia was compensated for by an unusually acute sense of smell, and who was, moreover, no mean botanist, that he could have classified the plants according to their smell had there been a sufficiency of olfactory terms for the purpose ; then we have the thousand effluvia, some pleasant and others not so pleasant, of living animals, including the various races of mankind ; next come the—mostly repulsive—odours of decaying vegetable and putrefying animal matter ; and finally the products of man's own proud ingenuity and skill, such as the artificial perfumes and flavours on the one hand and on the other coal-gas, acetylene, carbon disulphide, and the like.
Parker notes it as worthy of remark that man has created, both accidentally and intentionally,
