82 LECTURE IIL 



striation is altogether internal and not external. The 

 membrane in itself is perfectly smooth and even ; the 

 transverse striation belongs to the contents, which, when 

 seen in a mass, form the red substance of the muscle. 



Now it is this substance which has the property of 

 contractility indubitably inherent in it, and even varies 

 in appearance according to its state of contraction, be- 

 coming broader when contracted, whilst the intervals 

 between the individual transverse bands become some- 

 what narrower, so that a change in the arrangement of 

 its minutest constituents takes place, and this, as seems 

 probable from the investigations of Brucke, not merely 

 in the case of its physical molecules, but also in that of 

 its visible anatomical constituents. Brucke, namely, 

 by examining muscle by polarized light, has discovered 

 different optical properties in the individual layers of 

 substance in those which compose the transverse striae 

 and those which form the intervening mass. On the 

 adoption of certain methods of preparation, every pri- 

 mitive muscular fasciculus appears to be made up of 

 plates or discs of a different nature, piled up one above 

 -another, and these in their turn to be entirely composed 

 of minute granules (Bowman's sarcous elements). In 

 reality, however, the contents of a primitive fasciculus 

 consist of a certain number of fine, longitudinal fibrils, 

 every one of which contains minute granules correspond- 

 ing in position to the transverse striae or apparent discs 

 of the primitive fasciculus, and held together by a pale, 

 intervening substance. Now, since a considerable num- 

 ber of primitive fibrils lie in apposition side by side, 

 there arises, in consequence of the symmetrical position 

 of the little granules, this very appearance of discs which 

 really do not exist. In proportion to the activity of the 

 muscle these parts assume an altered position with re- 

 gard to one another ; during contraction the granules 



