Observations on the minute structure and mode of contraction of voluntary muscular fibre : being the abstract of a paper read before the Royal Medical Society, Edinburgh, December 15th, 1848 / by W. Murray Dobie.

  • Dobie, William M. (William Murray), 1828-1915.
Date:
[1849]
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the minute structure and mode of contraction of voluntary muscular fibre : being the abstract of a paper read before the Royal Medical Society, Edinburgh, December 15th, 1848 / by W. Murray Dobie. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    of unsti'iated muscles in some Filarias and in a Vesicularia, a swelling took place in the centre of the fibre which thus became shorter and thicker. Dr. A. Farre observed a similar fact in the unstriated muscles of the Polypifera. The admirable researches of Mr. Bowman have left us little to wish for with regard to the nature of the contraction ; I refer to his observations published in the ' Philosophical Transactions' for 1842. A.11 his observations were made on muscular fibres of animals shortly after death. I shall briefly allude to some observations made with reference to this subject on the living and uninjured tadpole. In April this year (1848), when observing the circulation in the tail of a tadpole after the disappearance of the gills, I was surprised on noticing that the ci'oss-striated muscular fibres were distinctly visible through the external tegument; the contrac- tions after the animal was somewhat exhausted were slow and beautiful, not uniform throughout, as is the case when the tail is observed immediately after the death of the animal and stripped of its integument: the former is the active, living and voluntary, the latter the passive contraction. When the contraction was comparatively slow, the approach of the transverse strise could be seen with extreme distinctness ; the relaxation was as instantaneous as the contraction in that part of the fibre which was the subject of it. The circulation of the blood was visibly accelerated after a rapid series of contractions; the blood seemed to be pressed out of the vessels of the part undergoing contraction; on relaxation taking place the afflux was immediate. These observations were made at a time when I was much en- gaged with other matters, and are consequently very imperfect. I hope to be able to resume the inquiry during the ensuing spring, when these interesting animals can be obtained in a pro- per state for U*e examination. I believe this is the first obser- vation of the contraction of a cross-striated muscle, so high in the scale of being as the Batrachia. I may mention that Dr. Allen Thomson repeated my experiments on the tadpole about the same time and with similar results. Among the Eotifera I have observed very beautiful examples of cross-striated muscle, more especially in the Euchlanis tri- quetra and in the Euchlanis Hornemanni, which are not uncom- mon species; the approach of the transverse strise is very marked. The relaxed fibres are subject to a degree of zigzag flexure when other muscles of the animal are in action. In conclusion, one word on the mode of displaying or separa- ting fibrillse from the mass of a fibre, which is unquestionably a B