Volume 1

The works of John Hunter / edited by James F. Palmer.

Date:
1835-37
Catalogue details

Licence: Public Domain Mark

Credit: The works of John Hunter / edited by James F. Palmer. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    But, besides pressure, there are other properties of matter. Many bodies have qualities besides being tangible ; some only when in solu- tion making an impression on the tongue and causing taste ; the same bodies when thrown into vapour give smell: air, besides being tangible, has a peculiar motion, arising from its repulsive quality, called vibra- tion, which strikes the ear and produces hearing. There arises another property in another species of matter, called light, which we know less of than any other, which has a power of pervading some bodies, called transparent, and gives us the sensation of sight; and from peculiarity in the formation of those transparent parts light becomes more deter- mined in its direction. The sensation of the glans penis, tickling, and itching would seem to belong to feeling. The first, however, is certainly a different mode of action of the nerve from common feeling, and both itching and tick- ling require a particular mode of impression to produce them. An animal can bear with ease a certain quantity of common sensa- tion, which quantity being particularly applied will give pleasure; but if common sensation be increased beyond certain bounds, it gives great pain ; so that pain is no more than an increased sensation, such as the sense of violence committed to a part* *. All the five senses are subject to the same mode of sensation when applied in the same way, namely, by touch, and if the impression is too strong, give the sensation of pain. For instance, if the retina be hurt, it gives pain, but not light; if the ear be hurt, it gives pain, but not sound; if the nose be hurt, it gives pain, but not smellf. But there which they are specially fitted to convey. This opinion is not warranted by more recent discoveries. An impression on the retina, of whatever kind, excites the sensation of light. Majendie found that on touching the retina with a couching-needle no pain was excited, but the sensation of light: a blow on the eye has the same effect. If pressure be made with the finger on the sclerotic, a dark spot will be seen immediately at the point of pressure, where the function of the nerve is probably impeded, with a halo of light surrounding it. Of the auditory nerve we know little; and on the tongue and nose the gustatory and olfactory nerves are so intermixed with the fibres of the fifth or nerve of feeling, that it is not easy to distinguish between their actions in such an expe- riment; but galvanism, which excites a pricking sensation in the skin, causes a peculiar flavour when applied to the tongue ; and the smell of the electric fluid is well known.] * [If this were the case, we should expect to find pain differing only in degree, but not in kind. Some structures, as bone, ligament, and the fibrous structures generally, exhibit no common sensation, although they are acutely alive to pain under circum- stances of injury and disease.] f [To each of these organs are distributed branches of the fifth nerve, or the nerve of sensation ; it is by means of these that common sensation is furnished to the organs of sense, and through them that lesions excite the feeling of pain. See the preceding note.]