Renewed inquiries concerning the spiral structure of muscle, with observations on the muscularity of cilia / by Martin Barry, M.D.

  • Martin Barry
Date:
[1852]
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Licence: Public Domain Mark

Credit: Renewed inquiries concerning the spiral structure of muscle, with observations on the muscularity of cilia / by Martin Barry, M.D. 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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    the fibrils. Transverse cleavage of the primitive fasciculus is caused by the spirals giving way at that pai't where they offer the least resistance, viz. at the part where they cross one another imd are in contact. The sarcolemma arises from the coalescence if spirals. It was by attending to the history of development of muscle, chiefly in the larva of the large toad of Jersey, that the author laarrived at a knowledge of the foregoing facts. His observations published in the present paper were made with one of the large compound microscopes of Plossl; and it happened that the in- sstrument was the very last constructed by that justly renowned ooptician. The following are some of the new facts herewith ooDserved; others will be mentioned further on. The two spirals of which the muscular fibril consists^ run in the same direction, and not in opposite directions, as the author at first supposed. (Plate I. fig. 1.) These two spirals are united at the end of the fibril, as in a loop. Such at least is the case in one form of muscle, PI. II. fig.30, :and from analogy it may be presumed to be the same in others. The fibril, being thus a double or twin spii-al, undergoes a stronger twisting in contraction, and an imtwisting in relaxation. A'\Tieu met with in relaxation, the two spirals usually present tthemselves in a state comparable to that of common twine, s (PI. I. fig. 2.) Between the untwisting in relaxation and the twisting in con- ttraction, there are sevei-al intermediate states. Fig. 3 presents four ssuch intermediate states seen in different parts of the same fibril. Cilia also are double spiral threads, and thus have a structure Hike that of the muscular fibril. (Figs. 39, 30, 31, &c.) The author then describes models of lead wire which he has econstructed for the purpose of illustrating the structure of the nmuscular fibril, fig. 1. These models, though veiy rude ones, nmay afford some idea of the different conditions of the fibril in rregard to length, breadth, and thickness, in different degrees of ccontraction, a, and relaxation, b. {b, in the model, fig. 1, repre- isents part of a, after the drawing of the latter out*.) It is an error to suppose it possible to learn how the strise in umuscle are produced, by examining merely the primitive fasci- cculus. The primitive fasciculus must be, as far as possible, teased oout with needles, and the fibrillse separately examined. To obtain Uhe fibril, muscle should be selected in which the primitive fas- ccieuli are small. For this purpose the heart is especially to be * [Such models have since been presented to the Royiil Society and to tithe Royal College of Surgeons in London by the Author.—May 1862.] A 2