STRUCTURE OF MUSCULAR FIBRES. 283 



of the muscular fibres, and also, each of the ultimate filaments, 

 according to Prochaska and Rudolphi, extend the whole length 

 of the fleshy part of the muscles, differing entirely in this respect 

 from the ultimate structure of the bones. 



Anatomists do not agree in regard to the diameter assigned 

 the ultimate muscular filament, and from its microscopical 

 diminutiveness any measurement can be considered as little 

 more than an approximation. They have been examined by 

 Hook, Lewenhoeck, Dehayde, Muys, and more recently still by 

 Prochaska and others. According to Prochaska, they are 

 generally straight and parallel with each other, flattened or 

 prismatic, and of a diameter one-fifth of that of the red globules 

 of blood. Autenreith supposed them equal to one-third of the 

 diameter. Prevost and Dumas found them by their measure- 

 ment, ^th part of an inch in diameter, five or six times 

 smaller than the red globules of the blood, and nearly equal, 

 as Miiller also has asserted, to the diameter of the chyle 

 globules, or to the central nuclei of the red globules of blood, 

 which may be considered the most minute compound constitu- 

 ents of the economy. 



The more recent microscopical measurements of Henle, Lauth, 

 Ficinis, Bruns and others, agree in giving to the ultimate or 

 elementary muscular filament of animal life, a diameter of T gooo^h 

 part of an inch. The diameter of the primitive fasciculus, com- 

 monly called muscular fibre, which is cylindrical in shape, is 

 considered upon an average about J s th part of an inch in diame- 

 ter. Each one is marked by striae or streaks, which pass trans- 

 versely round them, in slightly curved or wavy parallel lines 

 from fl^gg to T 2ooo tn f an i ncn apart. 



The nature of these striae which belong solely to the mus- 

 cles of animal life, are not well understood, whether they be 

 delicate fibres wound round the primary fasciculi, mere wrinkles 

 in its myolemma or sheath, or what seems more likely, depres- 

 sions corresponding with the breaks between the globules or 

 granules, which, appended end to end, constitute a primitive 

 filament. According to the microscopical observations of Messrs. 



