885 



Fig. 2. Gross-section of a normal muscle- 

 fibre of a plaice; one sees the transversely 

 cut cylindric bundles of fibrils in the 

 centre -and a small layer of ribbon shaped 

 bundles on the edge (Zenker's liquid, iron- 

 haematoxylin, enlargement 600). 



Fig. 3. Gross-section of a fibre of the 

 muscle-knob. One sees two concentric 

 parts : an interior part with fibrils which 

 are transversely cut and an exterior 

 part with circular fibrils, (formalin, 

 ironhaematoxylin, enlargement 500). 



part shows the cross-cut longitudinal fibrils, while in the exterior part only 

 circular fibrils are visible. Between the two parts a narrow fissure is generally to 

 be seen (Fig. 3 and 4). 



Fig. 4. Fotograph in which a great number 

 of fibres as mentioned in fig. 3, are visible. 



In longitudinal sections we see, that the circular fibrils do not appear along the 

 whole length of the fibre but are localized to one or more places, while the muscle 

 fibre has become here more voluminous (Fig. 5). The fissure between the central 

 and peripheral fibrils is not always present: here and there longitudinal fibrils bend 

 aside and join the circular-ones (Fig. 6). 



