Report on the progress of human anatomy and physiology in the year 1842-3 / [Sir James Paget].

  • James Paget
Date:
1844
Catalogue details

Licence: Public Domain Mark

Credit: Report on the progress of human anatomy and physiology in the year 1842-3 / [Sir James Paget]. Source: Wellcome Collection.

    18/32 (page 18)
    of clogs, but the results were inconclusive. Thej' tended, however, to prove that such a union does not take place ; for in several of the cases the connected portion of the two trunks were found, on subsequent examination, disparted, and each had united again with that portion of itself from which it had been separated. It was found that a sufficient union for the restoration of function can take place in three or four months, although a portion of a nervous trunk eight lines in length has been completely removed. Reflex action. Some evidence in favour of the view that the nerves of the excito- motory system form a system distinct from those conveying sensation and volition, is afforded by the investigations of Mr. Newport.* He finds that in the myria- poda the fibres which correspond to the true spinal cord in vertebrata are distinct from those connected with the cephalic ganglia. They form part of the cord in the intervals between the abdominal ganglia, and may be traced from the peri¬ phery into the several ganglionic centres, from which they pass backwards along the cord until they arrive at the next ganglion, from which they pass again to the surface of the body. Now there is reason to believe that the ganglia are not sen¬ sitive ; for the reflex acts, which are repeatedly performed after the removal of the head or destruction of the central ganglia, are performed without any appear¬ ance of volition being exercised in them and always in one and the same manner. Influence of the nervous centres. Professor Volkmann,f one of the most accu¬ rate experimenters of modern times, has occupied himself in testing the value of those experiments which are supposed to prove the direct influence of the central nervous organs upon the movement of the viscera. With regard to the part of the centres on which the movements of the heart de¬ pend,—Volkmann show's that in fresh-slain animals the movements of the heart are so completely irregular, even when left to themselves—in one half minute hurried, in the next retarded, then stopping for one or more minutes and then of themselves going on again—that it is impossible to determine the influence of any supposed excitant of the brain or spinal cord. From a great number of ex¬ periments, very carefully conducted, no fixed result could be arrived at except this, that the existence of any direct influence exerted on the heart by irritating the nervous centres is as yet altogether doubtful. He has come to the same conclusion, upon equally good negative evidence, in regard to the effects supposed to be produced on the motions of the stomach and in¬ testines by irritating the brain and cord. He could find no such influence exerted. The motions of the alimentary canal often entirely cease for a long time, and are then of themselves renewed; but when once they have entirely ceased, no irrita¬ tion of the nervous centres can reproduce them, although it is certain that after the canal ceases to move the nervous centres are still irritable. He peremptorily de¬ nies Budge’s experiment in which he believed that though the peritoneum of* the abdominal walls was left, the intestines moved when the central organs were irri¬ tated and ridicules the active inflation of the stomach, which Budge supposed to be thus produced. With equal positiveness he denies the truth of Budge’s state¬ ments respecting the elevation and expansion of the testicle when a part of the ce¬ rebellum is irritated. In repeated trials he could produce no such effects as Budge reports, in either the digestive canal or the testes.His conclusion is, “ I am far from • On the structure, relation, and development of the nervous and circulatory systems . in the Myriopoda, &c.. Transactions of the Royal Society, 1843. See also Br. and For. Med. Review, vol. XVI, p. 160, et seq., in which, in the review of Arnold and M. Hall on the reflex theory, both this and all the other evidence for the anatomical distinctness of the excito-motory system are adduced, with the exception of the obser¬ vations by Van Deen presently to be mentioned. [Since the preceding was in type I have been favoured with the perusal of the further analysis of Mr. Newport’s works con¬ tained in an earlier part of this Number, to which I must refer as affording a more com¬ plete account of them than could be inserted in the text.] t Muller’s Archiv, 1S42, Heft v. f The accuracy of several others of Dr. Budge’s experiments and deductions is im¬ pugned by Dr. Stilling in Haeser’s Archiv, 1842, Heft i, and in Schmidt’s Jahrbucber, 1843, Heft ii, iii, <fcc.