Sensation and the unity of structure of sensiferous organs / Professor Huxley.

  • Huxley, Thomas Henry, 1825-1895.
Date:
[1879]
Catalogue details

Licence: Public Domain Mark

Credit: Sensation and the unity of structure of sensiferous organs / Professor Huxley. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    causation. Assuming the existence of an external world, there is no difficulty in obtaining experimental proof that, as a general rule, olfactory sensations are caused by odorous bodies ; and we may pass on to the next step of the inquiry—namely, how the odorous body produces the effect attributed to it. The first point to be noted here is another fact revealed by ex- perience ; that the appearance of the sensation is governed, not only by the presence of the odorous substance, but by the condition of a certain part of our corporeal structure, the nose. If the nostrils are closed the presence of the odorous substance does not give rise to the sensa- tion ; while, when they are open, the sensation is intensified by the ap- proximation of the odorous substance to them, and by snuffing up the adjacent air in such a manner as to draw it into the nose. On the other hand, looking at an odorous substance, or rubbing it on tho skin, or holding it to the ear, does not awaken the sensation. Thus, it can be readily established by experiment that the perviousness of the nasal passages is, in some way, essential to the sensory function; in fact, that the organ of that function is lodged somewhere in the nasal passages. And, since odorous bodies give rise to their effects at considerable distances, the suggestion is obvious that something must pass from them into the sense organ. What is this something which plays the part of an intermediary between the odorous body and the sensory organ ? The oldest speculation about the matter dates back to Democritus and the Epicurean School, and it is to be found fully stated in the fourth book of Lucretius. It comes to this: that the surfaces of bodies are constantly throwing off excessively attenuated films of their own substance; and that these films, reaching the mind, excite the appropriate sensations in it. Aristotle did not admit the existence of any such material films, but conceived that it was the form of the substance, and not its matter, which affected sense, as a seal impresses wax, without losing anything in the process. While many, if not the majority, of the Schoolmen took up an intermediate position, and supposed that a something which was not exactly either material or im- material, and which they called an “ intentional species,” effected the needful communication between the bodily cause of sensation and the mind. But all these notions, whatever may be said for, or against, them in general, are fundamentally defective, by reason of an oversight which was inevitable, in the state of knowledge at the timo in which they were promulgated. What the older philosophers did not know, and could not know, before the anatomist and physiologist had done his work, is that, between the external object and that mind in which they supposed the sensation to inhere, there lies a physical obstacle. The sense organ is not a mere passage by which the “ tenuia simulacra rerum,” or the “ intentional species ” cast off by b 2