110 Mr. W. M. Dobie on the Minute Sti'ucture and 



ments advanced, than that of voluntary muscle, so that even at 

 the present time it must still be considered a question by no 

 means set at rest. 



My object in the present communication is to state briefly 

 the opinions which a careful examination of this texture in seve- 

 ral animals has led me to adopt, confining my observations to the 

 elementary fibre, independent of its sarcolemmal sheath. 



Before proceeding to do so, I shall very shortly notice the 

 opinions of the principal microscopic anatomists who have been 

 employed in this investigation. 



Robert Hooke and Leuwenhoek were the first to examine 

 muscular fibre with the microscope. Robert Hooke speaks of 

 the " fibres resembling a necklace of pearl ;" it is probable that 

 by fibres he means the ulthnatc fibrillse. 



Leuwenhoek saw and figured the transverse strise, which he 

 regarded as only surface-markings produced by the windings of 

 a spiral thread. He considered the fibre to be composed of glo- 

 bules, less in size than the corpuscles of the blood. He made 

 cross-sections of the fibres, and showed them to be polygonal and 

 surrounded by areolar texture. 



Malpighi, in an isolated passage of his works, notices the 

 transverse strise. De Heide also described and figured them. 



In the large work of iMuys, which appeared in the middle of 

 the last century, the author describes muscle with great care ; he 

 w^as evidently acquainted with the transverse strise, and figured 

 the fibrillse, which he terms "fila," and describes as "nonnun- 

 quam etiam nodosa " (PI. VII. fig. \ab cd). The nodose appear- 

 ance would seem to have perplexed him, and he considered it not 

 universal. Muys was well-aware of the solidity of the elementary 

 fibres, and his drawings of cross-sections of muscle are well- 

 worthy of examination. 



Prochaska wrote an excellent treatise on muscle* ; he supposed 

 that the markings seen on the surface of a muscular fibre were 

 caused by the lateral pressure of vessels, nerves or fibres. He 

 injected muscle very successfully, and found the vessels so nu- 

 merous, that he attributed the contraction of muscle to the dis- 

 tension of these vessels throwing the fibre into zigzag flexures. 



Fontana, in his treatise " On the Venom of the Viper f," 

 makes some short but excellent observations on muscular fibre ; 

 he was the first anatomist who ascribed the transverse strise to 

 the lateral coaptation of the sarcal elements of the fibrillse. He 

 thus speaks of the fibrillse : — 



" Les fils chai-nus primitifs sont des cyhndres solides, egaux 

 entr'eux, et marques visibleinent a distances egales de petits 

 signes, comme d'autant de petits diaphragmes, ou rides. Je n^ai 



* De Carne Musciilari. f ^"i* '^ Venin de la Vipere, 1781. 



