320 STRUCTURES IN A MUSCULAR FIBRE. [BOOK I. 



by subjecting yet living and rapidly frozen muscular fibres to pressure 

 we can express from the interior of the fibre a somewhat viscous 

 but yet perfectly liquid substance, to which, he gave the name of the 

 muscle-plasma, which shortly afterwards, if the temperature be 

 favourable, sets as a soft jelly: doubtless in consequence of the 

 coagulation of a proteid body of which the precursor or precursors 

 existed in solution. Kiihne had the good fortune to observe on one 

 occasion living muscular fibres, within the sarcolemma of which a 

 living nematode (subsequently again seen by Eberth 1 and indentified 

 by him as tne Myoryctes Weismanni) freely moved about. This worm 

 was able to make its way from one end to the other of the muscular 

 fibre, displacing in its course (but only temporarily) the sarcous 

 elements, and in a way which left no room for doubt that the creature 

 was moving in a fluid medium in which were suspended the aii- 

 isotropous constituents of the fibre. Kiihne was thus led to the 

 conception that in the voluntary muscular fibre the contents consist 

 of anisotropous solid bodies the sarcous elements which are 

 suspended in a viscous liquid, contraction consisting essentially of a 

 change in the form of the suspended bodies. 



Objections have been raised to this view of Klihne's, some of which 

 are based upon microscopic observations, others upon the difficulty 

 which their advocates have experienced in accounting satisfactorily for 

 the orderly arrangement of the anisotropous elements, on the hypothesis 

 that these are simply suspended in a viscous liquid. 



Krause, as we have already pointed out, believes that the structure, 

 which since his description of it has gone by the misleading term of 

 'Krause's membrane' (viz. the anisotropous structure in the light band 

 of resting muscle), is attached to the sarcolemma, so that according to 

 him a muscular fibre would be divided into a series of transverse 

 compartments. But excellent observers who have followed him 

 (Engelmann), deny the existence of a membrane, the existence of 

 which is absolutely disproved by the fortunate observation of 

 Kiihne. 



Such a view as Krause's might have been held before the time of 

 Kiihne's famous observation, but the latter, it appears to us, supplies 

 a certain criterion for rejecting the former. On physical grounds it has 

 been shewn by Briicke, and is maintained in his most recently pub- 

 lished writings by Hermann, that the existence of a system of trans- 

 verse partitions in the muscular fibre would oppose a great (and use- 

 less) resistance to the forces which bring about the changes in its form. 



The difficulties w r hich some have experienced in explaining the 

 orderly arrangement of the anisotropous elements are, as Kiihne 

 points out, dispelled if we surmise that this orderly arrangement is 

 dependent (1) on the pressure exerted upon the contents of the fibre 

 by the sarcolemma, and (2) on the mutual attraction which leads solid 

 bodies, floating in a liquid, to adhere one to another. 



1 Eberth, Zeitschriftf. wissensch. Zoologie, Vol. xn. (18.63), p. 530. 



