264 



SPECIAL HISTOLOGY. 



Fig. 109. 

 ^ J5 



tion, to restore the pristine position of the lips, angle of the mouth, &c. 

 An actual distortion, therefore, dependent upon persistent muscular 

 contraction, can only take place in consequence of morbid conditions of 

 the central organs. 



In the investigation of the muscles it is necessary that they should be 

 studied in the fresh state, and with the aid of various reagents. The 

 primitive fasciculi are most easily isolated in muscles which have been 

 boiled or immersed in spirit, in which also, the transverse striag are for 

 the most part very well displayed, as is also the case after treatment 

 ■with corrosive sublimate or chromic acid. In the study of the transverse 

 strias, it is above all indispensable that the muscles should be viewed in 

 various degrees of extension and contraction (Fig. 109). The former 



conditions, which are well worth observation, are 

 readily viewed, if long slender muscles, such as 

 the hyoglossi of the Frog, &c., are examined on a 

 wooden stage having a central opening filled in 

 with glass. It will then be seen, when no exten- 

 sion whatever is employed, that the transverse 

 strise are narrow (about 0'0004 of a line) and very 

 closely approximated, and that the fasciculus itself 

 is broad ; whilst, when it is extended to the utmost, 

 the stripes are 0*0008 of a line wide, and placed 

 at the same distance apart, and that the fasciculus is narrower. The 

 contractions must be observed either in fresh muscles still quivering, and 

 kept moist with serum, albumen, or vitreous humor ; or in the way pro- 

 posed by E. Weber, — and which consists in the galvanizing, by means 

 of the rotation apparatus, of the muscle to be examined, such, for in- 

 stance, as the abdominal muscles and slender muscles of the extremities 

 in the Frog, the diaphragm and cutaneous muscles of the smaller Mam- 

 malia, &c. For this purpose the muscle must be placed upon a piece of 

 looking-glass, from a small space in the middle of which the metallic 

 coating has been removed. One of the conducting wires is brought 

 through an opening in the stage, or else affixed to it so as to be im- 

 movably in contact with one of the portions of tinfoil. If the muscle 

 now be viewed under a magnifying power of 100 linear, whilst the second 

 conducting wire is brought in contact with the other portion of tinfoil, 

 the moment the circuit is completed, its fibres will be seen to contract in 

 a rectilinear direction, and at the same time to become thicker, whilst 

 the transverse strice are more closely approximated [vide Fig. 109, which 

 represents both a contracted and an extended muscle). The muscular 

 fibres remain in this condition so long as the galvanic influence is kept 



Fig. 109. — A primitive fasciculus of a Frog's muscle in different degrees of extension : 

 A, the fasciculus, stretched and slender, with broad distant transverse strire ; B, the same not 

 extended, broader, and with narrower, closely approximated striae — Magnified 350 diameters^ 



