On some cutaneous nerve-terminations in mammals / by George Hoggan and Frances Elizabeth Hoggan ; communicated by James Murie.

  • Hoggan, George.
Date:
[1882]
Catalogue details

Licence: Public Domain Mark

Credit: On some cutaneous nerve-terminations in mammals / by George Hoggan and Frances Elizabeth Hoggan ; communicated by James Murie. 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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    point out the share which the habits of the animal have had in forming so apparently unique an organ out of elements existing plentifully in every mammal, and show that, in short, it is merely formed by a combination of the invariable intraepithelial nerves of the locality, common to all the Mammalia, with the nerve-endings belonging to the hairs or whiskers. These latter, by the peculiar digging movements of the Moles, have so often been torn out that finally the hairs have become entirely suppressed, although the arrangements of the nerve-terminations upon tbeir follicle remain behind; and these, modified in appearance by the absence of the hair, now go to form what is known as the organ of Eimer. In the original article in which Eimer* announced his discovery of that organ, he states that if a live Mole be confined in a vessel, it soon shows, by the manner in which it feels all over the walls of its prison with its proboscis, that that structure must possess the sense of touch in a high degree; and it seems to have been this behaviour on the part of the Mole which induced Eimer to search for and discover its peculiar nerve-apparatus. He also enlarges upon the special anatomical richness of the snout in such nerve-organs, which he enumerates as amounting to 5000; and he holds that, physiologically, the sensitiveness is demonstrated by the fact that a smart tap on the nose kills the animal. Let us, however, remark in passing, that if all the hairs were plucked out of any particular part of this animal's or of any other animal's body, and the shrinking together which this would entail in the part operated upon be taken into consideration, the nerve-supply would appear to be equally plentiful with what is seen upon the Mole's proboscis. Thus Eimer has somewhat exaggerated the anatomical importance of the part, in nerves, just as he has mag- nified its physiological importance, as those who know the extreme sensitiveness of the smaller Shrews to impressions even upon their tails, may easily conceive. It was similar watching of the habits of Eats which led Jobert to look for tactile hairs on the tails of those animals, and to prove to his own satisfaction that the exis- tence of such hairs (8552 in number, according to his enumeration) rendered the tail a tactile organ. He also thought that he settled the matter completely by cutting off a Rat's tail and finding that thereby its agility was impaired—the fact, however, being that what ' Die Schnauze des Maulwurfs als Tasfcwerkzoug, Archiv fiir niikrosko- pischo Anatomie, 1871, vol. vii. p. 181. 41*