282 STRUCTURE OF MUSCULAR FIBRES. 



the elementary particles of cellular tissue likewise pass. In- 

 the muscles of organic life, the cellular tissue is less abundant, 

 but more dense than in those of animal life. In some parts, 

 especially in the digestive canal it is so dense and resistant as 

 to represent a sort of ligamentous tissue, and give attachment 

 to muscular fibres. 



This delicate sheath surrounding the primary fasciculus, has 

 been designated by Mr. Bowman as the sarcolemma, or the 

 primitive cellular investment of the muscular fibres. The term 

 myolemma has been applied to the same structure by Mr. Wil- 

 son and Dr. Quain. 



The entire muscle thus appears naturally susceptible of three 

 subdivisions. 1st. Into fasciculi, or bundles of fibres. These 

 are the minutest subdivisions which can be made with the 

 naked eye, without resort to boiling or other mechanical means. 

 These are themselves collected into bundles, by septa which 

 pass in from the general sheath of the muscles, but which are 

 easily unraveled by a little dissection ; so that what is at first 

 sight mistaken by the student for a fasciculus, is in reality a 

 bundle of fasciculi. The size of each of these fasciculi, varies 

 in the different mtiscles of the body, and occasionally in the 

 same muscle, according to the number of fibres of which it is 

 composed. 2nd. Into fibres so called or the primitive fasciculi. 

 These are rendered very apparent by boiling, as seen daily in 

 culinary preparations, by which the muscular fibre is swoln, 

 while the cellular envelop, at the same time softened and 

 reduced to a gelatinous pulp, is readily burst. These fibres 

 also vary in their thickness, some having a diameter three or 

 four times as great as that of others, depending upon the num- 

 ber of elementary filaments usually amounting to several hun- 

 dred of which it is composed. 3d. Into the elementary, or 

 ultimate muscular filaments. These are wholly microscopical, 

 are not uniform in their diameter in all muscles, (those of organic 

 life being much smaller,) and vary considerably in the numbers 

 taken to constitute the muscular fibres of different size.* Each 



* Meckel. torn. i. p. 378. 



