236 B. MELLAND. 



On contraction the fibre becomes shorter and thicker, the transverse 

 rows of dots approach one another and appear darker, probably by 

 contrast with the now bright "dim" disc. These appearances are 

 similar to those seen in the " fixed waves of contraction," described 

 in the osmic acid preparations. 



In a preparation of fresh muscle I have seen a fibre undergo slow 

 rigor mortis, commencing at one end and gradually extending towards 

 the other. It exactly resembled a very slow contraction wave passing 

 over the fibre, and the changes undergone by successive discs, as 

 the contraction affected them, were similar in appearance to those 

 described in fig. 18, and could be observed with more deliberation 

 than usual. 



The Fibre under Polarised Light. — The effects observed in the 

 living fibre with crossed Nicols were exactly similar to those figured 

 and described by Briicke and Schafer (' Quain's Anat.,' 9th ed., vol. ii, 

 fig. 125). Briicke's drawing is almost identical with diagram 3. 



The fibre is chiefly made up of doubly refractile or anisotropous 

 material, but a band of singly refractile or isotropous material crosses 

 the fibre transversely in the position of each Krause's membrane, and 

 this band is seen with a high power to consist of a row of rhomboidal 

 dots. Fine lines of isotropous material are described running longi- 

 tudinally across the anisotropous discs and joining the rhomboidal 

 dots. The appearance of the muscle fibre under polarised light leads 

 us to the belief that the network consists of isotropous, the matrix or 

 ground substance of anisotropous or doubly refracting, material. 



V. Alcohol Preparations. 



Alcohol preparations of muscle show, in most cases, a somewhat 

 different character to those prepared by the preceding methods. 



Spirit has a tendency to split the fibre into fibrils and sarcous 

 elements. After the muscle has been in alcohol it may be stained 

 with some reagent ; Kleinenberg's hematoxylin, for instance, gives 

 excellent results. Alum carmine may also be used. Mount in Canada 

 balsam. 



Absolute alcohol has a somewhat different effect from ordinary spirit. 

 It sometimes seems to fix the fibre as it appears during life — that is, 

 there is no differentiation into sarcous elements, but transverse rows of 

 dots, and longitudinal lines are alone seen, as in the living fibre. Fixed 

 waves of contraction may also be found. 



