On the development of striated muscular fibre in Mammalia / by William S. Savory ; presented by James Paget.

  • Savory, William Scovell, 1826-1895.
Date:
[1855]
Catalogue details

Licence: Public Domain Mark

Credit: On the development of striated muscular fibre in Mammalia / by William S. Savory ; presented by James Paget. 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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    mate, so that the fibre is at this part much narrower; and still further on the nuclei are more completely separated ; they are again oval, with their long axis now in the direction of the fibre; the borders have united, and the diameter of the fibre is consequently very considerably diminished. This falling-in of the lateral bands, as the nuclei separate, and their ultimate coalescence, affords evidence for believing, that when they were separated, there could have existed but very little intermediate sub- stance between them amongst the nuclei. As a general rule, the changes just described proceed uniformly throughout the entire fibre. But in most specimens some fibres will be found in which development has advanced more rapidly towards one extremity than at the other, and these serve admirably to illustrate the changes which occur. Soon after the nuclei have separated some of them begin to decay. They increase in size ; their outline becomes indistinct; a bright border appears immediately within their margin ; their contents become decidedly granular; their outline is broken and interrupted; and presently an irregular cluster of granules is all that remains, and these soon disappear. With regard to these groups of granules, however, it is worthy of remark, that as the fibres continue to increase in length, and the remaining nuclei are still further separated, they are extended longitudinally and the granules become more scattered. It sometimes happens that an irregularity may be observed in the separation of the nuclei. Here and there two or more occasionally remain in con- tact, as if adherent. This lengthening of the fibre, and consequent separation of the nuclei, is due to an increase of material, and not to a stretching of the fibre*, for the lateral bands, although they grow firmer, do not decrease in width as they approach each other; they preserve their size. Occasionally, indeed, they appear a little narrower, as if stretched, but this is rare, and is no doubt due to manipulation. The fact is, as these lateral bands fall in and coalesce, their breadth undergoes no apparent alteration. They remain separated for a time at those parts of the fibre where the nuclei are, but they ultimately join, and the nuclei lie imbedded between them. The changes described above are generally most obviously marked, and are there- fore more readily traced in those fibres which are formed at the earliest period. In those of later growth, the lengthening of the fibres does not commence so early, or proceed so rapidly, and is therefore not so obvious, for the nuclei usually decay be- fore they are separated to any extent. Indeed, in some of the fibres this separation of the majority of the nuclei seems scarcely to occur at all; while but a small inter- val exists between them, and while their oval form is still preserved, most of them perish in their places, with their long axis still lying transversely; and the position they occupied is marked for a time by clusters of granules extended transversely at frequent intervals along the course of the fibre. (See Plate X. fig. 9a&cc.) In these fibres, however, the same essential changes occur. They subsequently * As Schwann described it, Untersuchungen, &c.