i ORGANISATION AND STRUCTURE OF MUSCLE 17 



lamella, and does not stain with any other reagent. The lamella 

 itself remains colourless. This, as will presently appear, arises from 

 a reaction common to all muscles on the one hand, of the plas- 

 matic ground- substance, on the other, of the contractile fibrils 

 which thus affords an invaluable means of studying the distribu- 

 tion of the two within one fibre. From this reaction we may 

 conclude that the interfibrillar substance (which of course forms a 

 a spiral lamella) is identical with the axial sarcoplasm, so that the 

 cortical substance in other cases also should contain formative 

 plasma in addition to the con- ^^ __^__ m ___^______.. 



tractile fibrils, as is directly C| ^W^ 



proved by the radial striation 



of the cross - sections. There 



is, however, a deplorable lack 



of any systematised compara- f^J 



tive observations on the finer 



structure of invertebrate muscle {jj^&i 



according to modern methods. 



Knoll (13), writing on the mSjt * \(ff,^^ 



relative scarcity and abund- 

 ance of protoplasm in muscle- 

 fibres, communicated numerous 

 data, which, however, bear less 

 on the finer structure of the 

 cortical substance than on the 

 proportion between sarcoplasm 



and Contractile Substance in FIG. 9. Transverse section of muscle-cell from 

 ,i (. j the mantle of Eledone moschata. (Ballowitz.) 



the muscles of vertebrate and 



invertebrate animals. From these, as well as from earlier re- 

 searches (H. Fol, 14), it is evident that the muscle-cells of Lamelli- 

 branchs and Gasteropoda have in many cases the same structure 

 as those of Cephalopoda. The appearance of double oblique 

 (in many cases also of transverse) striation in the muscle-cells of 

 the adductor muscle of the Lamellibranchs is very interesting. 

 Fol, previous to Ballowitz, had established an analogous theory 

 of structural relations, since he described the contractile sheath 

 of the spindle-cells as consisting of fibrils running spirally round 

 the plasmatic axis. Like Ballowitz, he referred the figure of 

 quadratic or rhombic arese, first described by Schwalbe, simply to 

 the crossing of the two halves of the spiral windings, running 



c 



