642 HENRY M. BERNARD, 



from the action of stains, points strongly to the nuclear character of 

 the anisotropous layers. 



Further, in muscles which have the nuclei arranged in rows along 

 the axes of the fibres, a correspondence, which may be accidental, 

 between the nuclei and the anisotropous layers ') has been observed 

 by VosSELEE, as quoted by Eimer ^). 



More important still, however, is the fact that in well- stained 

 muscle fibres of Galeodes the nuclei appear not to stain (Fig. 26, 27, 28). 

 Whereas, in one whole series of sections the nuclei are well stained 

 (Fig. 29), but the muscle fibres themselves are unstained. It is not 

 easy to avoid the suggestion that the staining matter is in the one 

 case in the fibrils and in the other in the nuclei, i. e. that the sub- 

 stances are identical (cf. further Fig. 4). 



The variations in the arrangement of the staining substance must 

 have some significane. Sometimes there are 3 bands (Fig. 27, cf. also 

 the accessory discs found in Crustacean muscles), at others 2 (cf. the 

 staining substance in Crustacean muscles divided by a very variable 

 Hensen's disc) and at others again only 1 band (Figs. 26, 29). May 

 not this mean that the staining substance is in a state of flux, — 

 being perpetually used up and renovated. That a large supply of 

 nuclein is of importance to striped muscle is evident from the great 

 number of nuclei found in the sarcoplasm (Fig. 29), and from the fact 

 that a great multiplication of the nuclei of the formative cells is one 

 of the first phases in the development of this tissue. 



Hensen's discs would then be an expression of the diminish- 

 ing quantity of staining substance which tends to mass at the 

 ends of the anisotropous layers in immediate contact with the iso- 

 tropous substance. It would be difficult to obtain direct evidence of 

 this; indirect evidence however seems to be afibrded by the Umkehrungs- 

 stadium, in which Hensen's disc is much widened. 



There is thus some very definite evidence in favour of the view 

 that the anisotropous layers are masses of nuclear substance. If this 

 is the case, then, as Verworn's general theory requires, the fibrils 



1) In the Arachnid Galeodes the nuclei (Fig. 29) seem sometimes 

 to break up so that a nuclear fragment corresponds with, a stripe, 

 but on the other hand, they seem occasionally to join end to end, so 

 that we have long rod-like nuclear masses. 



2) in: Zeitschrift f. wiss. Zool., Bd. 53, 1892. „Die Entstehung 

 und Ausbildung des Muskelgewebes, insbesondere der Querstreifung des- 

 selben, als Wirkung der Thätigkeit betrachtet". 



