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veral fasciculi of fibres, enveloped in a cellular sheath similar to that 

 which covers the muscle itself, and separates it from the surrounding 

 parts. Each fasciculus is formed of the union of a multitude of fibres, 

 so delicate, that anatomy cannot reduce them to their ultimate division, 

 and that the smallest distinguishable fibre is still formed by the juxta po- 

 sition of numerous fibrilhe of incalculable minuteness. As the last divi- 

 sions of the muscular fibre completely elude our means of investigation, 

 it would be very absurd to attempt to explain their minute structure, and, 

 after the example of Muys, to write a voluminous work on this obscure 

 part of physiology. Shall we say, with the above author, that each dis- 

 tinguishable fibre is composed of three fibrillse progressively decreasing 

 in size; with Leeuwenhoek, that the diameter of this elementary fibre is 

 only the hundred thousandth part of a grain of sand ; with Swamrfter- 

 dam, de Heyde, Cowper, Ruysch, and Borelli, that this primitive fibre 

 consists of a series of globular, rhomboidal molecules; with Lecat, that 

 it is nervous; with Vieussens and Willis, that it is formed by the extreme 

 ramifications of arteries; with others, that it is cellular, tomeritous, 8cc. 

 How is it possible to speak, with any degree of certainty, of the nature 

 of the parts of a whole, which, from its extreme minuteness, eludes our 

 most accurate investigations. To explain the phenomena of muscular 

 action, it is inefficient to conceive each fibre as formed of a series of mo- 

 lecules of a peculiar nature, united together by some unknown medium, 

 whether that be oil, gluten, or any other substance, but whose cohesion 

 is manifestly kept up by the vital power, since the muscles yield, after 

 death, to efforts by which, during life, they would not have been torn 5 

 and such is their tenacity, that they are very seldom ruptured*. 



These fibres, which, when irritated, possess, in the highest degree, the 

 power of shortening themselves of contracting, however minute one may 

 suppose them, are supplied with vessels and nerves. In fact, though they 

 are neither vascular nor nervous, as may be readily ascertained by com- 

 paring the vessels and nerves which enter into the structure of the mus- 

 cles, with that of these organs, and by attending to the difference of their 

 properties; each fibre receives^ the power of contracting, from the blood 

 brought to it by the arteries, and from the fluid transmitted from the 

 brain, along the nerves. A cellular sheath surrounds these fibrillae (and 

 the nerves and vessels perhaps terminate within it)f, others unite them 



* " M. BATTEH, by the assistance of his powerful microscope, discovered muscular 

 fibres to be chains of globules, and he conceived that they may be constructed from the 

 globules of fibrine arranged in lines. Copland. 



\ The majority of anatomists suppose that the muscular fibre itself is beyond the 

 circuit of the circulation, and this appears in some points of view the correct opinion, if 

 we attend to the form and size of the fibres, and to their connexions with the cellular 

 tissue ; but although we may grant that the red globules of the blood do not circulate 

 through the muscular fibres themselves, and that these globules pervade only the capil- 

 laries of the connecting cellular substance, still we must allow that they are formed and 

 afterwards supported, either by the vessels conveying red blood, assimilation taking 

 place, in the manner of a deposit from them, without any continuity of texture, or by 

 the medium of a direct communication and admixture of a particular series of capillary 

 terminations of vessels with the muscular fibres, into which the red globules cannot 

 enter owing to the great tenuity of these capillaries. If we choose the former alter- 

 native, which appears, however, the least probable, we may conceive that the nervous 

 terminations, in muscular parts, soften into an invisible pulp, and unite intimately with 

 the capillary vessels, and with the cellular texture, which connects the individual fibres; 

 and that the chain of globules, of which the fibres are composed, being acted on by the 

 influence resulting from the action of the nervous on the vascular terminations in the 



