ORGANISATION AND STRUCTURE OF MUSCLE 



45 



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verse discs, which are either completely isolated, or still lie within 

 the sarcoplasm ; this last is more or less swollen, and divided by 

 delicate partition walls, corresponding with the segment (Z), into 

 solitary cases or compartments arranged in longitudinal series, 

 each case containing a transverse disc, corresponding elsewhere 

 with the system of stria? (N J Qh Q J ' N). It is to be noted that" 

 the segments (QhQ) do not swell out as in the acid reaction, 

 but are only separated by alterations within the segment (Z). 

 The sarcoplasm appears to be constricted at the junction of the 

 partition walls, while the cases between bulge outwards. 



Bowman explains this bulging, which 

 is visible before the final breakdown into 

 discs, by the withdrawal of the sarcolemma 

 from the surface of the discs, to which it 

 adheres firmly. 



Eollett, on the contrary, observes with 

 justice that it is not merely the sarcolemma 

 that shrinks, but also a portion of the sarco- 

 plasm, which covers the inner side of the 

 sarcolemma in a sheet of varying thick- 

 ness, so that we are dealing 

 with a local vacuolation of the 

 muscle substance. 



Our own experiments lead 

 us to accept Eollett's explana- 

 tion of the alcohol disintegra- 

 tion into discs as entirely 

 satisfactory. He assumes that 



the endosmotic pressure of the fluid in the circular canals 

 originally present in the muscle increases considerably, but 

 at the segment (Z) possesses a certain firmness and resist- 

 ance, while the impinging layer (E) or (J) is very yielding, 

 and therefore liable to maceration from the fluid. This results 

 in the freeing of the intermediate layers as a disc within a 

 mpartment, the walls of which are formed above and below 

 segment (Z\ at the sides by the bulging of the primitive 



1. The peculiar resistance of the segment (Z) had already 

 n discovered by Engelmann. 



The figures which arise from this discoid disintegration of 

 he muscle-fibres might, of course, be interpreted on the theory 



FIG. 30. Muscle- 

 fibre of Opatrum 

 sabulosum broken 

 down into discs 

 (alcohol treat- 

 ment). (Rollett.) 



